Indexing doesn't work on specific yarn.lock file, why?

Created by: slimsag

This turns up no search results: https://k8s.sgdev.org/search?q=repo:%5Egithub%5C.com/sourcegraph/codeintellify%24+marked

Disabling indexing by adding index:no to the query fixes it: https://k8s.sgdev.org/search?q=repo:%5Egithub%5C.com/sourcegraph/codeintellify%24+marked+index:no

Other yarn.lock files work: https://k8s.sgdev.org/search?q=repo:%5E35%5C.247%5C.108%5C.89/repos/13/github%5C.com/sourcegraph/sourcegraph/%5C.git%24%40fb7acbf+%22helper-module-transforms%22

Why is this? What is it about this specific file that causes indexing on it to not work properly? @ryan-blunden also encountered this on a different sourcegraph/server instance