List of steps to reproduce (step by step, including full links if applicable):

• create a new url property like https://sweopendata.wiki.opencura.com/wiki/Property:P11
• try adding a statement using it https://sweopendata.wiki.opencura.com/wiki/Item:Q16
• -> error

What happens?:

What should have happened instead?:

Software version (if not a Wikimedia wiki), browser information, screenshots, other information, etc.: