diff --git a/src/solver/model_getters.jl b/src/solver/model_getters.jl
index 2655e70c17..ff2a4a0b81 100644
--- a/src/solver/model_getters.jl
+++ b/src/solver/model_getters.jl
@@ -12,7 +12,17 @@ end
 
 function get_model_config(parsed_args)
     config = parsed_args["config"]
-    @assert config in ("sphere", "column", "box", "plane")
+
+    valid_configurations = ("sphere", "column", "box", "plane")
+
+    if !(config ∈ valid_configurations)
+        error_message = string(
+            "config = $config is not one of the ",
+            "valid configurations $valid_configurations",
+        )
+        throw(ArgumentError(error_message))
+    end
+
     return if config == "sphere"
         SphericalModel()
     elseif config == "column"
diff --git a/src/solver/yaml_helper.jl b/src/solver/yaml_helper.jl
index 00c980dea4..8cc41f5597 100644
--- a/src/solver/yaml_helper.jl
+++ b/src/solver/yaml_helper.jl
@@ -72,7 +72,17 @@ function override_default_config(config_dict::AbstractDict;)
     for k in intersect(keys(config_dict), keys(default_config))
         default_type = typeof(default_config[k])
         v = config_dict[k]
-        config[k] = isnothing(default_config[k]) ? v : default_type(v)
+
+        # Attempt to convert user value `v` to the same type as
+        # the default. If that fails, throw an informative error.
+        config[k] = try
+            isnothing(default_config[k]) ? v : default_type(v)
+        catch err
+            user_entry_type = typeof(v)
+            msg = """Configuration entry "$(k)" = $v has type $(user_entry_type),
+                     but must have type $default_type."""
+            throw(ArgumentError(msg))
+        end
     end
 
     # The "diagnostics" entry is a more complex type that doesn't fit the schema described in