[BACKEND] actual fix

src/ytdl_sub/script/script.py

@@ -288,6 +288,14 @@ class Script:
                 unresolvable=unresolvable,
             )
 
+        for lambda_func in current_var.lambdas:
+            if lambda_func.value in self._functions:
+                subset_to_resolve |= self._recursive_get_unresolved_output_filter_variables(
+                    current_var=self._functions[lambda_func.value],
+                    subset_to_resolve=subset_to_resolve,
+                    unresolvable=unresolvable,
+                )
+
         return subset_to_resolve
 
     def _get_unresolved_output_filter(

src/ytdl_sub/script/types/variable_dependency.py

@@ -171,7 +171,17 @@ class VariableDependency(ABC):
         -------
         True if it contains all input variables as a dependency. False otherwise.
         """
-        for custom_function in self.custom_functions:
+        # If there are lambdas, see if they are custom functions. If so, check them
+        custom_functions_to_check = self.custom_functions
+        for lambda_func in self.lambdas:
+            if lambda_func.value in custom_function_definitions:
+                custom_functions_to_check.add(
+                    ParsedCustomFunction(
+                        name=lambda_func.value, num_input_args=lambda_func.num_input_args()
+                    )
+                )
+
+        for custom_function in custom_functions_to_check:
             if not custom_function_definitions[custom_function.name].is_subset_of(
                 variables=variables, custom_function_definitions=custom_function_definitions
             ):

src/ytdl_sub/validators/string_formatter_validators.py

@@ -241,6 +241,10 @@ def _validate_formatter(
     variable_names = {var.name for var in parsed.variables}
     custom_function_names = {f"%{func.name}" for func in parsed.custom_functions}
 
+    for lambda_func in parsed.lambdas:
+        if lambda_func in mock_script.function_names:
+            custom_function_names.add(lambda_func.value)
+
     if not variable_names.issubset(mock_script.variable_names):
         raise StringFormattingVariableNotFoundException(
             "contains the following variables that do not exist: "

tests/unit/script/types/test_lambda_function.py

@@ -81,7 +81,7 @@ class TestLambdaFunction:
             Script(
                 {
                     "the_array": "{ ['a', 'B', 'c', 'D'] }",
-                    "output": "{ %array_apply(the_array, %lower) }",
+                    "output": "{ %array_apply(the_array, %custom_cap) }",
                     "should_lower": "{%bool(True)}",
                     "%custom_cap": """{
                         %if(