username can not be empty

server_controller.py

@@ -45,10 +45,12 @@ def register():
     missing = missing_attributes(['username', 'password'])
     if missing:
         return bad_request(missing)
-    username = request.json['username']
+    username = request.json['username'].strip()
+    if username == '':
+        return bad_request('Username can not be empty.')
     hashed_password = sha256_crypt.encrypt(request.json['password'] + salt)
     if model.user_exists(username):
-        return forbidden('User already exists.')
+        return bad_request('User already exists.')
     game_key = ''
     if 'game_key' in request.json:
         game_key = request.json['game_key'].strip().upper()