Merge pull request #6709 from RyanCavanaugh/fix6662

Don't crash when return type jsdoc tag is malformed

src/compiler/checker.ts

@@ -10380,9 +10380,11 @@ namespace ts {
 
         function getReturnTypeFromJSDocComment(func: SignatureDeclaration | FunctionDeclaration): Type {
             const returnTag = getJSDocReturnTag(func);
-            if (returnTag) {
+            if (returnTag && returnTag.typeExpression) {
                 return getTypeFromTypeNode(returnTag.typeExpression.type);
             }
+
+            return undefined;
         }
 
         function createPromiseType(promisedType: Type): Type {