[release] src/goInstallTools.ts: return a rejected promise when go isn't found

If Go is not found, return a rejected promise, so, the promise
chaining can work. updateGoVarsFromConfig is not declared as an
async, so returning nothing means returning nothing.

Fixes #660

Change-Id: I16f73ca057f3b6bb220a754afc1baa43cc891c22
Reviewed-on: https://go-review.googlesource.com/c/vscode-go/+/255963
Run-TryBot: Hyang-Ah Hana Kim <[email protected]>
TryBot-Result: kokoro <[email protected]>
Trust: Hyang-Ah Hana Kim <[email protected]>
Reviewed-by: Suzy Mueller <[email protected]>
(cherry picked from commit 8e9cae7)
Reviewed-on: https://go-review.googlesource.com/c/vscode-go/+/257603

Author: hyangah

src/goInstallTools.ts

@@ -347,7 +347,7 @@ export function updateGoVarsFromConfig(): Promise<void> {
 	const goRuntimePath = getBinPath('go', false);
 	if (!goRuntimePath) {
 		suggestDownloadGo();
-		return;
+		return Promise.reject();
 	}
 
 	return new Promise<void>((resolve, reject) => {
@@ -482,7 +482,7 @@ async function suggestDownloadGo() {
 	}
 
 	const choice = await vscode.window.showErrorMessage(
-		`Failed to find the "go" binary in either GOROOT(${getCurrentGoRoot()}) or PATH(${envPath}. ` +
+		`Failed to find the "go" binary in either GOROOT(${getCurrentGoRoot()}) or PATH(${envPath}). ` +
 		`Check PATH, or Install Go and reload the window.`,
 		'Go to Download Page'
 	);