Bad objects/ API response when object ID does not exist

[genghisken]

Get a 500 error if the objectId does not exist when requesting object lightcurve.

[HeloiseS]

NOTE: in the ConeSerializer we return a message which may or may not contain the word error and we use that to get the views to return the correct error code back to the caller. We need to return to correct status code at the moment we just return the same code for many errors → we can expand to make it more accurate.

this will fix the problem for all API bits that might return specific HTTP error codes