bug fix

xero.php

@@ -198,9 +198,15 @@ class Xero {
             'urlResourceOwnerDetails' => 'https://api.xero.com/api.xro/2.0/Organisation'
           ]);
       
-          $newAccessToken = $provider->getAccessToken('refresh_token', [
-            'refresh_token' => $this->storage->getRefreshToken()
-          ]);
+          try {
+            $newAccessToken = $provider->getAccessToken('refresh_token', [
+                'refresh_token' => $this->storage->getRefreshToken()
+            ]);
+
+          }catch (\Exception $e) {
+             $this->startAuthorization();
+            return;
+          }
       
           // Save my token, expiration and refresh token
           $this->storage->setToken(