WMS HTTP Status codes that provide better feedback to the users.

[Jeffrey-Vervoort-KNMI]

Although the WMS is before REST standards, it would be nice to have similar HTTP codes for monitoring and as feedback to the users of the service.

Expected Behavior

When a user gives invalid input the server responds with a HTTP status code 4xx and a message.

Current Behavior

When a user gives invalid input the server responds with a clear message about what is wrong with the input, but a different status code than I would expect (200/500).
For example, when giving temperatured as input to the COVERAGE parameter. The status code is 500. And the message is Layer [temperatured] not found WCS GetCoverage Request failed. Other examples are in the table below.

Parameter	Input	Status code	Expected
COVERAGE	temperatured	500	404
dataset	Tx1d	500	404
BBOX	3.0,50.0,7.0,99999999999999.0	500	422
Time	2022-sdfsd-22T00:00:00Z/2022-07-23T00:00:00Z	500	422
CRS	EPSG:4326d	500	422
RESX/RESY	0.000004	500	422
RESX/RESY	0.d4	200	422
SERVICE	Tx1d	200	422
REQUEST	GetCoveraged	200	422

[Jeffrey-Vervoort-KNMI]

What I came across but did not see as part of the issue, but still might be interesting to know is:

• BBOX outputs NetCDF on incorrect value, e.g. “3.0,5sdfew0.0,7.0,54.0”
• FORMAT always outputs NetCDF on incorrect value, e.g. "arandomstring" as input
• TIME almost always outputs a NetCDF on very strange datetimes: 2022-027-22T00:00:00Z/2022-07-23T00:00:00Z
• ELEVATION always outputs a NetCDF also on random input: "3289urjf"