Add additional error handling

[princessmittens]

Tying up loose ends in the repo:

• Currently the api returns a zip file which is actually a json file when the error. What the repo returns should reflect the type of file. I.e. if returning a zip, it should be a .zip extension and vice versa for a json.
• Requests to pygeoapi are currently not handled, these should be wrapped in a try/except block.
• Remove unnecessary generated files created from a request.
• General refactoring where necessary.