Orphaned menu links bring down the site

I was starting to see that the source of the issue heading down what you have ended up patching. I also decided to take a look at the db tables as I suspect that rogue router entries were part of the cause of the issue. After node was uninstalled, router still contained 16 entries for paths containing node. I'm not sure why these entries were/are still around. Removing them also caused the issue to disappear.

I realized I was also able to wipe out the entries in the router table and that was rebuild so that would also fix the issue.

Since the router table had the stale entries, it doesn't seem like the router rebuild function (which happens upon cache flush at \Drupal::service('router.builder')->rebuild();) is not wholly working as it should be.

I think this particular occurence of the issue is the node/add link in the tools menu. It has a 'system' module and so it's not removed and I presume we could patch that somehow. But that's just the occurence of this issue: I don't think that a broken link should immediately and unrecoverably bring down your site.

Yes, what not_chx said. we talked about this in IRC. I debugged and this is certainly called from menu links, not router entries.

i.e. #2185967: Menu links no longer get removed if you uninstall the module they are provided by

Even simpler version.

Menu links not being cleared correctly are a symptom of routers not being cleared out properly. But I will create another issue on this topic.

The patch looks good to me.

Should fix the test failures.

This sounds directly related to #2185967: Menu links no longer get removed if you uninstall the module they are provided by, which is in turn blocked by #2177041: Remove all implementations of hook_menu

Agreed. Mentioned that in #9.

I wonder whether we can at least the failures? There needs to be a way to not fail silent. Hiding things is bad, at least this is my opinion.

you mean at least log the failures? I am sure there's a way but I do not know how to log errors in Drupal 8 (or do anything else. I just looked at where the exception is thrown and stopped it from propagating).

I checked core/core.services.yml for "log" but there's nothing (at least nothing relevant).

I like trigger_error() for cases like this (not everyone else does, but it's the only way you get both logging and errors displayed on screen during development).

It seems slightly mad to catch our own exceptions that we are throwing in the same class. I would personally just wait on the referenced issues above to fix this. Then if this does happen, it is an actual problem.

Yep. Let's do this.

The patch at #2200185-10: Router table is not cleared when modules are uninstalled should also resolve this issue.

I think it might be worth keeping something from this issue. You never know what people will do to their sites.