From a08af77b70c8c63509a2f8bfea922e5f14c79e0c Mon Sep 17 00:00:00 2001
From: Alan Agius <alan.agius4@gmail.com>
Date: Tue, 14 Aug 2018 16:26:44 +0200
Subject: [PATCH] refactor: fix return type of `tryCall` (#25481)

PR Close #25481
---
 packages/language-service/src/ts_plugin.ts | 21 ++++++++++-----------
 1 file changed, 10 insertions(+), 11 deletions(-)

diff --git a/packages/language-service/src/ts_plugin.ts b/packages/language-service/src/ts_plugin.ts
index d805a2668d..e021355fe9 100644
--- a/packages/language-service/src/ts_plugin.ts
+++ b/packages/language-service/src/ts_plugin.ts
@@ -26,51 +26,50 @@ export function create(info: any /* ts.server.PluginCreateInfo */): ts.LanguageS
   const proxy: ts.LanguageService = Object.create(null);
   let oldLS: ts.LanguageService = info.languageService;
 
-  function tryCall<T>(fileName: string | undefined, callback: () => T): T {
+  function tryCall<T>(fileName: string | undefined, callback: () => T): T|undefined {
     if (fileName && !oldLS.getProgram() !.getSourceFile(fileName)) {
-      return undefined as any as T;
+      return undefined;
     }
     try {
       return callback();
-    } catch (e) {
-      return undefined as any as T;
+    } catch {
+      return undefined;
     }
   }
 
-  function tryFilenameCall<T>(m: (fileName: string) => T): (fileName: string) => T {
+  function tryFilenameCall<T>(m: (fileName: string) => T): (fileName: string) => T | undefined {
     return fileName => tryCall(fileName, () => <T>(m.call(ls, fileName)));
   }
 
   function tryFilenameOneCall<T, P>(m: (fileName: string, p: P) => T): (filename: string, p: P) =>
-      T {
+      T | undefined {
     return (fileName, p) => tryCall(fileName, () => <T>(m.call(ls, fileName, p)));
   }
 
   function tryFilenameTwoCall<T, P1, P2>(m: (fileName: string, p1: P1, p2: P2) => T): (
-      filename: string, p1: P1, p2: P2) => T {
+      filename: string, p1: P1, p2: P2) => T | undefined {
     return (fileName, p1, p2) => tryCall(fileName, () => <T>(m.call(ls, fileName, p1, p2)));
   }
 
   function tryFilenameThreeCall<T, P1, P2, P3>(m: (fileName: string, p1: P1, p2: P2, p3: P3) => T):
-      (filename: string, p1: P1, p2: P2, p3: P3) => T {
+      (filename: string, p1: P1, p2: P2, p3: P3) => T | undefined {
     return (fileName, p1, p2, p3) => tryCall(fileName, () => <T>(m.call(ls, fileName, p1, p2, p3)));
   }
 
   function tryFilenameFourCall<T, P1, P2, P3, P4>(
       m: (fileName: string, p1: P1, p2: P2, p3: P3, p4: P4) =>
-          T): (fileName: string, p1: P1, p2: P2, p3: P3, p4: P4) => T {
+          T): (fileName: string, p1: P1, p2: P2, p3: P3, p4: P4) => T | undefined {
     return (fileName, p1, p2, p3, p4) =>
                tryCall(fileName, () => <T>(m.call(ls, fileName, p1, p2, p3, p4)));
   }
 
   function tryFilenameFiveCall<T, P1, P2, P3, P4, P5>(
       m: (fileName: string, p1: P1, p2: P2, p3: P3, p4: P4, p5: P5) =>
-          T): (fileName: string, p1: P1, p2: P2, p3: P3, p4: P4, p5: P5) => T {
+          T): (fileName: string, p1: P1, p2: P2, p3: P3, p4: P4, p5: P5) => T | undefined {
     return (fileName, p1, p2, p3, p4, p5) =>
                tryCall(fileName, () => <T>(m.call(ls, fileName, p1, p2, p3, p4, p5)));
   }
 
-
   function typescriptOnly(ls: ts.LanguageService): ts.LanguageService {
     const languageService: ts.LanguageService = {
       cleanupSemanticCache: () => ls.cleanupSemanticCache(),