Merge pull request microsoft#17044 from filipesilva/patch-1

rbuckton · web-flow · commit bb3253e544dc · 2017-07-10T11:47:48.000-07:00
Allow visitors to return undefined
diff --git a/src/compiler/types.ts b/src/compiler/types.ts
@@ -4339,7 +4339,7 @@ namespace ts {
      */
     export type Visitor = (node: Node) => VisitResult<Node>;
 
-    export type VisitResult<T extends Node> = T | T[];
+    export type VisitResult<T extends Node> = T | T[] | undefined;
 
     export interface Printer {
         /**
