fix(server): Fall back to bundled TS version if specified TSDK is too old (#1863)

We attempt to use the version of typescript defined in the extension
options. However, this might be too old for the required version in the
bundled Angular compiler. If this happens, we now attempt to resolve the
version from the bundled one instead (and print a warning to the output).

Fixes #1855

Author: atscott

server/src/version_provider.ts

@@ -51,8 +51,16 @@ export function resolveTsServer(probeLocations: string[]): NodeModule {
   if (probeLocations.length > 0) {
     // The first probe location is `typescript.tsdk` if it is specified.
     const resolvedFromTsdk = resolveTsServerFromTsdk(probeLocations[0], probeLocations.slice(1));
+    const minVersion = new Version(MIN_TS_VERSION);
     if (resolvedFromTsdk !== undefined) {
-      return resolvedFromTsdk;
+      if (resolvedFromTsdk.version.greaterThanOrEqual(minVersion)) {
+        return resolvedFromTsdk;
+      } else {
+        console.warn(`Ignoring TSDK version specified in the TypeScript extension options ${
+            resolvedFromTsdk
+                .version} because it is lower than the required TS version for the language service (${
+            MIN_TS_VERSION}).`);
+      }
     }
   }
   return resolveWithMinVersion(TSSERVERLIB, MIN_TS_VERSION, probeLocations, 'typescript');