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

• Go to https://freakylogo.miraheze.org/wiki/Special:ManageWiki/namespaces.
• Click the "Submit" button below the list of existing namespaces. Any namespace will work for this.
• Watch as MediaWiki gives you an error.

What happens?:
You get a "Fatal exception of type 'MWException'" error. I don't know if this is related to the db141 issue or not.

What should have happened instead?:
You're taken to a page in which you can modify the settings of the namespace you selected.

Browser information, screenshots and other applicable information:
I'm using Avast Secure Browser, which I think is Chromium-based. My version is 107.0.19254.107 (64-bit).