Massive refactoring in FormatMessage and LuaCallNode

Source/Integration/LuaCallNode.h

@@ -31,6 +31,7 @@ public:
 
 	//~ Begin UK2Node Interface.
 	virtual bool IsNodePure() const override { return false; }
+	virtual void ReconstructNode() override;
 	virtual bool NodeCausesStructuralBlueprintChange() const override { return true; }
 	virtual void ExpandNode(class FKismetCompilerContext& CompilerContext, UEdGraph* SourceGraph) override;
 	virtual ERedirectType DoPinsMatchForReconstruction(const UEdGraphPin* NewPin, int32 NewPinIndex, const UEdGraphPin* OldPin, int32 OldPinIndex) const override;
@@ -51,9 +52,15 @@ private:
 	static const FName ErrorPinName;
 
 private:
-	/** The lua function prototype, which must be saved as a property **/
+	// Whenever the function value changes, we call
+	// ReconstructNode, which backs up the value into this
+	// property.  This cache is needed because during
+	// ReconstructNode, we blow away the function pin.  The
+	// function pin is also absent when the node is first
+	// created.
+	//
 	UPROPERTY()
-	FString LuaFunctionPrototype;
+	FString LuaFunctionPrototype = TEXT("class.func(int arg1, int arg2) : int ret1, int ret2");
 
 };