Exclude prerelease tagged versions when fetching latest gopls version (…

…#2885)

src/goLanguageServer.ts

@@ -507,13 +507,19 @@ async function latestGopls(tool: Tool): Promise<semver.SemVer> {
 	// Coerce the versions into SemVers so that they can be sorted correctly.
 	const versions = [];
 	for (const version of data.trim().split('\n')) {
-		versions.push(semver.coerce(version));
+		const parsed = semver.parse(version, {
+			includePrerelease: true,
+			loose: true,
+		});
+		versions.push(parsed);
 	}
 	if (versions.length === 0) {
 		return null;
 	}
 	versions.sort(semver.rcompare);
-	return versions[0];
+
+	// The first version in the sorted list without a prerelease tag.
+	return versions.find(version => !version.prerelease || !version.prerelease.length);
 }
 
 async function goplsVersion(goplsPath: string): Promise<string> {
@@ -594,7 +600,7 @@ async function goProxyRequest(tool: Tool, endpoint: string): Promise<any> {
 	return null;
 }
 
-function goProxy(): string[]  {
+function goProxy(): string[] {
 	const output: string = process.env['GOPROXY'];
 	if (!output || !output.trim()) {
 		return [];