New checksum listing with dictionaries leads to confusing errors if you forget to update them

[Micket]

From a PR which had forgotten to inject new checksums

name = 'VTK'
version = '9.2.6'
...
checksums = [
    {'VTK-9.2.2.tar.gz': '1c5b0a2be71fac96ff4831af69e350f7a0ea3168981f790c000709dcf9121075'},
    {'VTKData-9.2.2.tar.gz': '4b0ac438c77773ff741fd02c0e3b0dc1406b4c51e6cbe4e8304306fa125f27bf'},
    {'vtk-version.egg-info': '787b82415ae7a4a1f815b4db0e25f7abc809a05fc85d7d219627f3a7e5d3867b'},
]

with the problem being that they are mapping to the old versions (and, of course, the checksums being old as well.
They are technically correct for version 9.2.2 (so there isn't actually any errors here if one were to nitpick)

but it does lead to a very confusing error message

== 2023-05-05 17:55:58,351 build_log.py:171 ERROR EasyBuild crashed with an error (at easybuild/easybuild-framework/easybuild/base/exceptions.py:126 in __init__): Invalid checksum spec 'None', should be a string (MD5) or 2-tuple (type, value). (at easybuild/easybuild-framework/easybuild/tools/filetools.py:1306 in verify_checksum)

Invalid checksum spec 'None'? It should detect the lack of a checksum for the particular source and give a proper error for that specifically.

[boegel]

Should be fixed with #4261

[Flamefire]

Should be fixed with #4261

It is rather fixed by #4150 and I think this is a good example why a missing key should be an error instead silently using None as the value: Forgetting to update that checksum dict is an error which would then go unnoticed until someone tries with enforce_checksums