/Edit: Solved the issue
For some time the, template Namespace appears in the category "Pages with script errors" in my home wiki.
Error message displayed on the template page is:
Lua error in Dev:Namespace_detect at line 18: Module:Namespace detect/data returned boolean, table expected.
We haven't changes anything on the template or module, in fact, we don't even use it anywhere. But here on Global Lua Modules/Namespace detect, it says "Test suite status: Failed". So I assume it's an issue with the dev module.
Unfortunately, I'm not into Lua at all, so someone with more experience should maybe look at this.
Thanks.