JavaScript error when hovering over token in PR diff

[nicksnyder]

Reproduce

1. Enable this extension
2. Go to https://github.com/sourcegraph/enterprise/pull/13690/files#diff-acd2ed24511b1af6436c32bb086afdc6
3. Hover over Test_getBySQL_permissionsCheck

Expected
Hover tooltip works

Actual

Error fetching hover from language server:
Request languageFeatures/$provideHover failed with message: Cannot read property 'length' of undefined

Workaround
Disable sourcegraph-string-references extension

Note: It works fine when viewed in sourcegraph https://sourcegraph.sgdev.org/github.com/sourcegraph/enterprise@d4776b4c954caa48a76805de46e0657172306bd9/-/blob/cmd/frontend/db/repos_perm_test.go?diff=d4776b4c954caa48a76805de46e0657172306bd9&utm_source=chrome-extension#L15:6