Fixed macro def expansion

Src/AST/Myc.Ast.Evaluator.pas

@@ -249,10 +249,10 @@ end;
 
 function TEvaluatorVisitor.VisitMacroDefinition(const Node: IMacroDefinitionNode): TDataValue;
 begin
-    // Macro definitions are compile-time constructs and should have been
-    // processed and removed from the AST by the TMacroExpander.
-    // If we encounter one here, it's a compiler pipeline error.
-    raise Exception.Create('Macro definitions cannot be evaluated at runtime.');
+    // Macro definitions are compile-time constructs.
+    // The MacroExpander leaves them in the AST for the Visualizer.
+    // The Evaluator must simply ignore them.
+    Result := TDataValue.Void;
 end;
 
 function TEvaluatorVisitor.VisitQuasiquote(const Node: IQuasiquoteNode): TDataValue;