Because $token refs an object, this statement will always be true. Therefore an empty oauth_token param will be added to each request, wich will break Bitbucket authorization process.

To fix this, we need to check if token key is empty and ignore it.

src/JacobKiers/OAuth/Request/Request.php

@@ -157,7 +157,7 @@ class Request implements RequestInterface
             'oauth_nonce' => Request::generateNonce(),
             'oauth_timestamp' => Request::generateTimestamp(),
             'oauth_consumer_key' => $consumer->getKey());
-        if ($token) {
+        if ($token->getKey()) {
             $defaults['oauth_token'] = $token->getKey();
         }