Dossier has a `default_scope { kept }`.
Because of that, when the parent dossier is discarded, `champ.dossier`
will return nil.
We should kill the default scope. But meanwhile, ensure that
`champ.dossier` returns even a discarded dossier.
We have quite a lot of `Error reading file` errors when uploading files.
These errors are generated by ActiveStorage `file_checksum.js` component
but it eats the actual reason of errors.
(See https://github.com/rails/rails/blob/5-2-stable/activestorage/app/javascript/activestorage/file_checksum.js#L38)
We can't really override the class to generate better errors, as they
are deeply nested in ActiveStorage class hierarchy, and not exported to
external code.
Instead, we hook into the FileReader event handler, to insert a logger
when this error occur. The original event handler will also still be
called as usual.
This is intended to be temporary. The debug code will be removed once
we get a better idea of what is going on.
A DirectUpload may fail for several reasons, and return many types of
errors (string, xhr response, Error objects, etc).
For convenience, wrap all these errors in a FileUploadError object.
- It makes easier for clients of the Uploader class to handle errors;
- It allows to propagate the error code and failure responsability.
In Sentry, when an `ActionController::InvalidAuthenticityToken` error
occurs, the breadcrumbs mention that before hitting the error, the user
clicked on one of those links.
Unfortunately we don't know which one. For debugging purposes, adding
classes to the links should allow us to see which links users are
navigating to.
DirectUpload returns errors as strings, including an HTTP status and a
file name (and without a stack trace).
But Sentry groups issues according to the stack trace, and maybe the
error message in last resort.
So we have an issue: as all DirectUpload errors logged by Sentry are
generated on the same line, with random-looking messages, Sentry groups
them either too or too little aggressively.
Instead of creating all the errors on the same line:
- add some `if`s statements to create them on different lines (and so
with different stack traces),
- strip the file name from the error message.
This allows Sentry to group the errors properly, with meaningful error
messages.
