Check if config is nothing before accessing fields (#281)

* Check if config is nothing before accessing fields

* Explicitly return

Co-authored-by: Will Tebbutt <willtebbutt00@gmail.com>

* Instantiate default config on the fly

* Add a test for config=nothing

---------

Co-authored-by: Will Tebbutt <willtebbutt00@gmail.com>

Project.toml

@@ -1,7 +1,7 @@
 name = "Mooncake"
 uuid = "da2b9cff-9c12-43a0-ae48-6db2b0edb7d6"
 authors = ["Will Tebbutt, Hong Ge, and contributors"]
-version = "0.4.5"
+version = "0.4.6"
 
 [deps]
 ADTypes = "47edcb42-4c32-4615-8424-f2b9edc5f35b"

ext/MooncakeLogDensityProblemsADExt.jl

@@ -59,8 +59,12 @@ function logdensity_and_gradient(∇l::MooncakeGradientLogDensity, x::Vector{Flo
 end
 
 # Interop with ADTypes.
+function getconfig(x::ADTypes.AutoMooncake)
+ c = x.config
+ return isnothing(c) ? Mooncake.Config() : c
+end
 function ADgradient(x::ADTypes.AutoMooncake, ℓ)
- debug_mode = x.config.debug_mode
+ debug_mode = getconfig(x).debug_mode
  if debug_mode
  msg = "Running Mooncake in debug mode. This mode is computationally expensive, " *
  "should only be used when debugging a problem with AD, and turned off in " *

test/integration_testing/logdensityproblemsad_interop.jl

@@ -24,6 +24,10 @@ test_gradient(x) = -2 .* x
  @test ADgradient(ADTypes.AutoMooncake(; config), l) isa typeof(∇l)
  @test parent(∇l) === l
 
+ # Check that nothing for config works.
+ @test ADgradient(ADTypes.AutoMooncake(; config=nothing), l) isa typeof(∇l)
+ @test parent(∇l) === l
+
  # Run in debug mode.
  debug_config = Mooncake.Config(; debug_mode=true)
  @test parent(ADgradient(ADTypes.AutoMooncake(; config=debug_config), l)) === l