src/goLint: fix type error caused by a bug in goLint

When gopls's staticcheck is used, the check fails with
a type error.

workbench.desktop.main.js:2247 TypeError: Cannot read property 'then' of undefined
	at Object.check (/Users/hakim/.vscode-insiders/extensions/golang.go-0.25.0/dist/goMain.js:58418)
	at runBuilds (/Users/hakim/.vscode-insiders/extensions/golang.go-0.25.0/dist/goMain.js:64847)
...

Callers of goLint expect Promise<ICheckResult[]>,
so return a resolved promise in case we want to skip
linting.

Change-Id: I41c92ca9f6f6a9b961acb7f07504fbd20135fcad
Reviewed-on: https://go-review.googlesource.com/c/vscode-go/+/321471
Trust: Hyang-Ah Hana Kim <[email protected]>
Run-TryBot: Hyang-Ah Hana Kim <[email protected]>
TryBot-Result: kokoro <[email protected]>
Reviewed-by: Rebecca Stambler <[email protected]>

Author: hyangah

src/goLint.ts

@@ -61,7 +61,7 @@ export function goLint(
 ): Promise<ICheckResult[]> {
 	const lintTool = goConfig['lintTool'] || 'staticcheck';
 	if (lintTool === 'staticcheck' && goplsStaticcheckEnabled(goConfig, goplsConfig)) {
-		return;
+		return Promise.resolve([]);
 	}
 
 	epoch++;