[document_repository] Improper error handling

[jeffersoncasimir]

Describe the bug
Certain errors are not properly reported. They return a generic "Please contact your administrator" message, caused by a Syntax error on the front-end due to the responses being invalid JSON.

These errors were: 413 (Request Entity Too Large) for test plan step 16 and a 403 (Forbidden), which occurred when initiating an upload, and logging out in another tab before completion.

Found during testing assignment #8519.

[driusan]

@kongtiaowang Can you look into fixing this? I think you just need to check resp.status and in the swal instead of saying "Please contact your administrator" have a permission denied (for 403) or file too large (for 413) error message.