net_uv: throw if Server.prototype.close() is called twice

Follows net_legacy behaviour.

lib/net_uv.js

@@ -631,10 +631,13 @@ function onconnection(clientHandle) {
 
 
 Server.prototype.close = function() {
-  if (this._handle != null) {
-    this._handle.close();
-    this._handle = null;
+  if (!this._handle) {
+    // Throw error. Follows net_legacy behaviour.
+    throw new Error('Not running');
   }
+
+  this._handle.close();
+  this._handle = null;
   this.emit('close');
 };
 

test/simple/test-http-unix-socket.js

@@ -75,8 +75,12 @@ server.listen(common.PIPE, function() {
 });
 
 process.on('exit', function() {
-  server.close();
   assert.ok(status_ok);
   assert.ok(headers_ok);
   assert.ok(body_ok);
+
+  // Double close should throw. Follows net_legacy behaviour.
+  assert.throws(function() {
+    server.close();
+  });
 });