Try improve error reporting

CHANGELOG.md

@@ -23,6 +23,8 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
   for this.
 - Implicit effects to set children now unparent all children when the effect is
   destroyed.
+- Error reporting should be improved with better formatting when effects invoke
+  other effects and no more loss of stack traces.
 
 ### Removed
 

src/apply.luau

@@ -1,7 +1,6 @@
 local typeof = game and typeof or require "../test/mock".typeof :: never
 
 local flags = require "./flags"
-local throw = require "./throw"
 local implicit_effect = require "./implicit_effect"
 local _, is_action = require "./action"()
 local graph = require "./graph"
@@ -67,7 +66,7 @@ local function process_properties(properties: Map<unknown, unknown>, instance: I
         if type(property) == "string" then
             if flags.strict then -- check for duplicate property assignment at nesting depth
                 if cache.nested_debug[depth][property] then
-                    throw(`duplicate property {property} at depth {depth}`)
+                    error(`duplicate property {property} at depth {depth}`, 0)
                 end
                 cache.nested_debug[depth][property] = true
             end
@@ -104,7 +103,7 @@ end
 -- applies table of nested properties to an instance using full vide semantics
 local function apply<T>(instance: T & Instance, properties: { [unknown]: unknown }): T
     if not properties then
-        throw("attempt to call a constructor returned by create() with no properties")
+        error "attempt to call a constructor returned by create() with no properties"
     end
 
     -- queue parent assignment if any for last

src/batch.luau

@@ -1,5 +1,4 @@
 local flags = require "./flags"
-local throw = require "./throw"
 local graph = require "./graph"
 
 local function batch(setter: () -> ())
@@ -11,14 +10,14 @@ local function batch(setter: () -> ())
         from = graph.get_update_queue_length()
     end
 
-    local ok, err: string? = pcall(setter)
+    local ok, err: string? = xpcall(setter, debug.traceback)
 
     if not already_batching then
         flags.batch = false
         graph.flush_update_queue(from)
     end
 
-    if not ok then throw(`error occured while batching updates: {err}`) end
+    if not ok then error(`error occured while batching updates: {err}`, 0) end
 end
 
 return batch

src/cleanup.luau

@@ -1,6 +1,5 @@
 local typeof = game and typeof or require "../test/mock".typeof :: never
 
-local throw = require "./throw"
 local graph = require "./graph"
 local get_scope = graph.get_scope
 local push_cleanup = graph.push_cleanup
@@ -14,14 +13,14 @@ local function helper(obj: any)
         elseif obj.disconnect then function() obj:disconnect() end
         elseif obj.Destroy then function() obj:Destroy() end
         elseif obj.Disconnect then function() obj:Disconnect() end
-        else throw("cannot cleanup given object")
+        else error "cannot cleanup given object"
 end
 
 local function cleanup(value: unknown)
     local scope = get_scope()
 
     if not scope then
-        throw "cannot cleanup outside a stable or reactive scope"
+        error "cannot cleanup outside a stable or reactive scope"
     end; assert(scope)
 
     if type(value) == "function" then

src/context.luau

@@ -1,4 +1,3 @@
-local throw = require "./throw"
 local graph = require "./graph"
 type Node<T> = graph.Node<T>
 local create_node = graph.create_node
@@ -44,10 +43,10 @@ local function context<T>(...: T): Context<T>
             if has_default ~= nil then
                 return default_value
             else
-                throw("attempt to get context when no context is set and no default context is set")
+                error("attempt to get context when no context is set and no default context is set", 0)
             end
         else -- set
-            if not scope then return throw("attempt to set context outside of a vide scope") end
+            if not scope then return error("attempt to set context outside of a vide scope", 0) end
 
             local value, component = ...
 
@@ -62,7 +61,7 @@ local function context<T>(...: T): Context<T>
             pop_scope()
 
             if not ok then
-                throw(`error while running context:\n\n{result}`)
+                error(`error while running context:\n\n{result}`, 0)
             end
 
             return result

src/create.luau

@@ -1,7 +1,6 @@
 local typeof = game and typeof or require "../test/mock".typeof :: never
 local Instance = game and Instance or require "../test/mock".Instance :: never
 
-local throw = require "./throw"
 local defaults = require "./defaults"
 local apply = require "./apply"
 
@@ -10,7 +9,7 @@ local ctor_cache = {} :: { [string]: () -> Instance }
 setmetatable(ctor_cache :: any, {
     __index = function(self, class)
         local ok, instance: Instance = pcall(Instance.new, class :: any)
-        if not ok then throw(`invalid class name, could not create instance of class { class }`) end
+        if not ok then error(`invalid class name, could not create instance of class { class }`, 0) end
 
         local default: { [string]: unknown }? = defaults[class]
         if default then
@@ -35,7 +34,7 @@ end
 local function clone_instance(instance: Instance)
     return function(properties: Props): Instance
         local clone = instance:Clone()
-        if not clone then throw "attempt to clone a non-archivable instance" end
+        if not clone then error "attempt to clone a non-archivable instance" end
         return apply(clone, properties)
     end
 end
@@ -47,7 +46,7 @@ local function create(class_or_instance: string | Instance, props: Props?): ((Pr
 	elseif typeof(class_or_instance) == "Instance" then
 		result = clone_instance(class_or_instance)
 	else
-		throw("bad argument #1, expected string or instance, got " .. typeof(class_or_instance))
+		error("bad argument #1, expected string or instance, got " .. typeof(class_or_instance), 0)
 		return nil :: never
 	end
 	if props then

src/graph.luau

@@ -1,4 +1,3 @@
-local throw = require "./throw"
 local flags = require "./flags"
 
 export type SourceNode<T> = {
@@ -22,9 +21,23 @@ export type Node<T> =  {
 
 local scopes = { n = 0 } :: { [number]: Node<any>, n: number } -- scopes stack
 
+local function efn(err: string)
+    local trace = debug.traceback(err, 2)
+
+    if string.find(err, "^effect error stacktrace") then -- if effect error is nested
+        trace = string.gsub("    " .. trace, "\n", function() -- indent entire error
+            return "\n    "
+        end)
+    end
+
+    trace ..= "\nsource update stacktrace:"
+return trace
+end
+
 local function ycall<T, U>(fn: (T) -> U, arg: T): (boolean, string|U)
+
     local thread = coroutine.create(xpcall)
-    local function efn(err: string) return debug.traceback(err, 3) end
+    --local function efn(err: string) return debug.traceback(err, 3) end
     local resume_ok, run_ok, result = coroutine.resume(thread, fn, efn, arg)
 
     assert(resume_ok)
@@ -45,9 +58,9 @@ local function assert_stable_scope(): Node<unknown>
 
     if not scope then
         local caller_name = debug.info(2, "n")
-        return throw(`cannot use {caller_name}() outside a stable or reactive scope`)
+        return error(`cannot use {caller_name}() outside a stable or reactive scope`, 0)
     elseif scope.effect then
-        throw("cannot create a new reactive scope inside another reactive scope")
+        error("cannot create a new reactive scope inside another reactive scope", 0)
     end
 
     return scope
@@ -81,8 +94,8 @@ end
 local function flush_cleanups<T>(node: Node<T>)
     if node.cleanups then
         for _, fn in next, node.cleanups do
-            local ok, err: string? = pcall(fn)
-            if not ok then throw(`cleanup error: {err}`) end
+            local ok, err: string? = xpcall(fn, debug.traceback)
+            if not ok then error(`cleanup error: {err}`, 0) end
         end
 
         table.clear(node.cleanups)
@@ -107,7 +120,7 @@ end
 
 local function destroy<T>(node: Node<T>)
     if flags.strict and table.find(scopes, node) then
-        throw("attempt to destroy an active scope")
+        error("attempt to destroy an active scope", 0)
     end
 
     flush_cleanups(node)
@@ -150,7 +163,7 @@ local function evaluate_node<T>(node: Node<T>)
             if not ok then
                 table.clear(update_queue)
                 update_queue.n = 0
-                throw(`effect stacktrace:\n{new_value :: string}`)
+                error(`effect error stacktrace\n{new_value :: string}`, 0)
             end
 
             node.cache = new_value :: T
@@ -170,7 +183,7 @@ local function evaluate_node<T>(node: Node<T>)
         if not ok then
             table.clear(update_queue)
             update_queue.n = 0
-            throw(`effect stacktrace:\n{new_value}\n`)
+            error(`effect error:\n{new_value}\n`, 0)
         end
 
         node.cache = new_value

src/lib.luau

@@ -18,7 +18,6 @@ local indexes, values = require "./maps"()
 local spring, update_springs = require "./spring"()
 local action = require "./action"()
 local changed = require "./changed"
-local throw = require "./throw"
 local flags = require "./flags"
 
 export type Source<T> = source.Source<T>
@@ -98,15 +97,15 @@ local vide = {
 setmetatable(vide :: any, {
     __index = function(_, index: unknown): ()
         if flags[index] == nil then
-            throw(`{tostring(index)} is not a valid member of vide`)
+            error(`{tostring(index)} is not a valid member of vide`, 0)
         else
             return flags[index]
         end
     end,
 
     __newindex = function(_, index: unknown, value: unknown)
         if flags[index] == nil then
-            throw(`{tostring(index)} is not a valid member of vide`)
+            error(`{tostring(index)} is not a valid member of vide, 0`)
         else
             flags[index] = value
         end

src/maps.luau

@@ -1,4 +1,3 @@
-local throw = require "./throw"
 local flags = require "./flags"
 local graph = require "./graph"
 type Node<T> = graph.Node<T>
@@ -20,7 +19,7 @@ local function check_primitives(t: {})
 
     for _, v in next, t do
         if type(v) == "table" or type(v) == "userdata" or type(v) == "function" then continue end
-        throw("table source map cannot return primitives")
+        error("table source map cannot return primitives", 0)
     end
 end
 
@@ -71,7 +70,7 @@ local function indexes<K, VI, VO>(input: () -> Map<K, VI>, transform: (() -> VI,
 
                     push_scope(scope)
 
-                    local ok, result = pcall(transform, function()
+                    local ok, result = xpcall(transform, debug.traceback, function()
                         push_child_to_scope(node)
                         return node.cache
                     end, i)
@@ -132,7 +131,7 @@ local function values<K, VI, VO>(input: () -> Map<K, VI>, transform: (VI, () ->
             local cache = {}
             for _, v in next, data do
                 if cache[v] ~= nil then
-                    throw "duplicate table value detected"
+                    error "duplicate table value detected"
                 end
                 cache[v] = true
             end
@@ -154,7 +153,7 @@ local function values<K, VI, VO>(input: () -> Map<K, VI>, transform: (VI, () ->
 
                 push_scope(scope)
 
-                local ok, result = pcall(transform, v, function()
+                local ok, result = xpcall(transform, debug.traceback, v, function()
                     push_child_to_scope(node)
                     return node.cache
                 end)

src/root.luau

@@ -1,4 +1,3 @@
-local throw = require "./throw"
 local graph = require "./graph"
 type Node<T> = graph.Node<T>
 local create_node = graph.create_node
@@ -14,21 +13,20 @@ local function root<T...>(fn: (destroy: () -> ()) -> T...): (() -> (), T...)
     refs[node] = true -- prevent gc of root node
 
     local destroy = function()
-        if not refs[node] then throw "root already destroyed" end
+        if not refs[node] then error "root already destroyed" end
         refs[node] = nil
         destroy(node)
     end
 
     push_scope(node)
 
-    local function efn(err: string) return debug.traceback(err, 3) end
-    local result = { xpcall(fn, efn, destroy) }
+    local result = { xpcall(fn, debug.traceback, destroy) }
 
     pop_scope()
 
     if not result[1] then
         destroy()
-        throw(`error while running root():\n\n{result[2]}`)
+        error(`error while running root():\n\n{result[2]}`, 0)
     end
 
     return destroy, unpack(result :: any, 2)

src/source.luau

@@ -9,7 +9,7 @@ export type Source<T> = (() -> T) & ((value: T) -> T)
 local function source<T>(initial_value: T): Source<T>
     local node = create_source_node(initial_value)
 
-    return function(...): T
+    local function update_source(...): T
         if select("#", ...) == 0 then -- no args were given
             push_child_to_scope(node)
             return node.cache
@@ -24,6 +24,8 @@ local function source<T>(initial_value: T): Source<T>
         update_descendants(node)
         return v
     end
+
+    return update_source
 end
 
 return source :: (<T>(initial_value: T) -> Source<T>) & (<T>() -> Source<T>)

src/spring.luau

@@ -1,4 +1,3 @@
-local throw = require "./throw"
 local graph = require "./graph"
 type Node<T> = graph.Node<T>
 type SourceNode<T> = graph.SourceNode<T>
@@ -114,7 +113,7 @@ local vec6_to_type = {
 
 local invalid_type = {
     __index = function(_, t: string)
-        throw(`cannot spring type {t}`)
+        error(`cannot spring type {t}`, 0)
     end
 }
 
@@ -141,7 +140,7 @@ local function spring<T>(source: () -> T, period: number?, damping_ratio: number
     -- todo: is there a solution other than reducing step size?
     -- todo: this does not catch all solver exploding cases
     if c > UPDATE_RATE*2 then -- solver will explode if this is true
-        throw("spring damping too high, consider reducing damping or increasing period")
+        error("spring damping too high, consider reducing damping or increasing period", 0)
     end
 
     local data: SpringState<T> = {
@@ -263,8 +262,6 @@ local function step_springs(dt: number)
     end
 end
 
-local remove_queue = {}
-
 local function update_spring_sources()
     for data, output in springs do
         local x0_123, x1_123, v_123,

src/switch.luau

@@ -1,4 +1,3 @@
-local throw = require "./throw"
 local graph = require "./graph"
 type Node<T> = graph.Node<T>
 type SourceNode<T> = graph.SourceNode<T>
@@ -32,15 +31,15 @@ local function switch<T, U>(source: () -> T): (map: Map<T, ((() -> U)?)>) -> ()
             if component == nil then return nil end
 
             if type(component) ~= "function" then
-                throw "map must map a value to a function"
+                error "map must map a value to a function"
             end
 
             local new_scope = create_node(owner, false, false)
             last_scope = new_scope :: Node<any>
 
             push_scope(new_scope)
 
-            local ok, result = pcall(component)
+            local ok, result = xpcall(component, debug.traceback)
 
             pop_scope()