Fail with better error messages if go binary cannot be found (microsoft#1543)

#17 Signed-off-by: Jan Koehnlein <jan.koehnlein@typefox.io>

Author: JanKoehnlein

src/goInstallTools.ts

@@ -292,6 +292,9 @@ export function updateGoPathGoRootFromConfig(): Promise<void> {
 
 // If GOPATH is still not set, then use the one from `go env`
 let goRuntimePath = getGoRuntimePath();
+if (!goRuntimePath) {
+return Promise.reject(new Error('Cannot find "go" binary. Update PATH or GOROOT appropriately'));
+}
 return new Promise<void>((resolve, reject) => {
 cp.execFile(goRuntimePath, ['env', 'GOPATH'], (err, stdout, stderr) => {
 if (err) {

src/util.ts

@@ -562,7 +562,16 @@ export interface ICheckResult {
  */
 export function runTool(args: string[], cwd: string, severity: string, useStdErr: boolean, toolName: string, env: any, printUnexpectedOutput: boolean, token?: vscode.CancellationToken): Promise<ICheckResult[]> {
 let goRuntimePath = getGoRuntimePath();
-let cmd = toolName ? getBinPath(toolName) : goRuntimePath;
+let cmd;
+if (toolName) {
+cmd = getBinPath(toolName);
+} else {
+if (!goRuntimePath) {
+return Promise.reject(new Error('Cannot find "go" binary. Update PATH or GOROOT appropriately'));
+}
+cmd = goRuntimePath;
+}
+
 let p: cp.ChildProcess;
 if (token) {
 token.onCancellationRequested(() => {