Handle Nop properly

Src/AST/Myc.Ast.Compiler.TypeChecker.pas

@@ -45,6 +45,7 @@ type
         function VisitAddSeriesItem(const Node: IAddSeriesItemNode): IAstNode; override;
         function VisitSeriesLength(const Node: ISeriesLengthNode): IAstNode; override;
         function VisitRecurNode(const Node: IRecurNode): IAstNode; override;
+        function VisitNop(const Node: INopNode): IAstNode; override;
 
         // Base cases (types are now set here)
         function VisitConstant(const Node: IConstantNode): IAstNode; override;
@@ -609,6 +610,12 @@ begin
     Result := TAst.AddSeriesItem(newSeries.AsIdentifier, newValue, newLookback, TTypes.Void);
 end;
 
+function TTypeChecker.VisitNop(const Node: INopNode): IAstNode;
+begin
+    // This is a leaf node. Assign its final type as Void.
+    Result := TAst.Nop(TTypes.Void);
+end;
+
 function TTypeChecker.VisitSeriesLength(const Node: ISeriesLengthNode): IAstNode;
 var
     seriesType: IStaticType;