Node with url field not accessible when created via code

Hello,

When I create a node with a url field via code ( both my own code and devel generate), i can't access the node via /node/nid. On my screen the following error shows up:

Fatal error: Unsupported operand types in path/to/project/core/lib/Drupal/Core/Utility/UnroutedUrlAssembler.php on line 188

When I look at my error messages a get the following:
Recoverable fatal error: Argument 2 passed to Drupal\Core\Utility\UnroutedUrlAssembler::assemble() must be of the type array, null given, called in path/to/project/drupal8test.local/core/lib/Drupal/Core/Url.php on line 743 and defined in Drupal\Core\Utility\UnroutedUrlAssembler->assemble() (line 60 of path/to/project/core/lib/Drupal/Core/Utility/UnroutedUrlAssembler.php).

Oddly enough, when i edit the node and save it, the node/nid page works.

I did a quick fix on my local project in the /core/lib/Drupal/Core/url.php in the function toString() :

public function toString() {
    if ($this->unrouted) {
+      if(empty($this->getOptions)) {
+        return $this->unroutedUrlAssembler()->assemble($this->getUri(), []);
+      }
+      else {
        return $this->unroutedUrlAssembler()->assemble($this->getUri(), $this->getOptions());
+      }
    }

I'm not shore if this is the correct way to solve it.