fix https://linear.app/tryghost/issue/SLO-88/typeerror-cannot-read-properties-of-null-reading-relations
- in the event that we make it through the version mismatch code, but
without a key, which is possible if you send a request like POST
/ghost/api/v2/content/posts/`, then the version mismatch code will try
and look up the API key attached to a null key, which won't work
- we should handle this case and soft return, to avoid trying to read
`.relations` from `null`
- I'm not entirely convinced by how this code works in general, it seems
quite confusing to reason about, but this commit should solve the HTTP
500 we've been seeing from this
- perhaps in the future we can return earlier in the flow if we receive
a `null` key
As discussed with the product team we want to enforce kebab-case file names for
all files, with the exception of files which export a single class, in which
case they should be PascalCase and reflect the class which they export.
This will help find classes faster, and should push better naming for them too.
Some files and packages have been excluded from this linting, specifically when
a library or framework depends on the naming of a file for the functionality
e.g. Ember, knex-migrator, adapter-manager
