create bin if not under go env GOPATH

src/main.ts

@@ -1,4 +1,5 @@
 import * as core from '@actions/core';
+import * as io from '@actions/io';
 import * as tc from '@actions/tool-cache';
 import * as installer from './installer';
 import * as path from 'path';
@@ -59,17 +60,25 @@ export async function run() {
   }
 }
 
-function addBinToPath(): boolean {
+async function addBinToPath(): Promise<boolean> {
   let added = false;
+  let g = await io.which('go');
+  if (!g) {
+    core.debug('go not in the path');
+    return added;
+  }
+
   let buf = cp.execSync('go env GOPATH');
-
   if (buf) {
-    let d = buf.toString().trim();
-    core.debug(`go env GOPATH: ${d}`);
-    let bp = path.join(d, 'bin');
+    let gp = buf.toString().trim();
+    core.debug(`go env GOPATH: ${gp}`);
+    if (fs.existsSync(gp)) {
+      let bp = path.join(gp, 'bin');
+      if (!fs.existsSync(bp)) {
+        core.debug(`creating ${bp}`);
+        io.mkdirP(bp);
+      }
 
-    if (fs.existsSync(bp)) {
-      core.debug(`${bp} exists`);
       core.addPath(bp);
       added = true;
     }