Errors can report non-existent tree/path combinations

[robrix]

I've seen a few errors come through Splunk (cf discussion in Slack) where the given repo_id/commit_oid combination exists, but doesn't have the repo_path—or in many cases anything even resembling the package_path at that or any other SHA in the repo. @hendrikvanantwerpen discovered that in at least one of these cases, the path in question does exist elsewhere in the repo's network. I guess everything really is somewhere. It's unknown whether that applies to all cases.

Ultimately, we're left with a few questions:

• where the heck is it finding this code?
• why does it want to index it?

I happen to only have seen this with JS, but that doesn't mean it's not happening with other languages or indexing strategies; I simply do not know.

[hendrikvanantwerpen]

I suspect this is an issue in Aleph instead of stack graphs. Perhaps we should transfer it?