[Feature]: Warning instead of error when reading values that are not valid according to the NWB schema

[ehennestad]

What would you like to see added to MatNWB?

When reading NWB files, different types of invalid values in the file will cause read errors. One example is if the schema specifies a attribute value to be constant (e.g. ElectricalSeries/data/unit should be volts), but the value of this attribute in the file is something else than the defined constant. For an example, see this discussion:
NeurodataWithoutBorders/helpdesk#75

Causing a file read error is perhaps too "dramatic", and a warning might be better.

@bendichter @rly @oruebel What are your thoughts here?

Is your feature request related to a problem?

Yes, files which have deviations from schema cannot be read. This can render a whole file useless, even if the issue is minor

What solution would you like?

I have two ideas in mind:

1. Very permissive read. Everything that is not according to schema causes a warning. The value being read is kept if possible.

2. A debug read mode. By default, reading files with invalid values causes an error, but support a debug flag / keyword argument that will change the error to a warning.

Do you have any interest in helping implement the feature?

Yes.

Code of Conduct

• I agree to follow this project's Code of Conduct
• Have you ensured this change was not already requested?

[rly]

I prefer Option 1. Pynwb does not block formerly valid data from being read. It will generally warn on reading of the file and block writing of invalid data. See these cases:
https://github.com/search?q=repo%3ANeurodataWithoutBorders%2Fpynwb%20_error_on_new_warn_on_construct&type=code
https://github.com/search?q=repo%3ANeurodataWithoutBorders%2Fpynwb%20_error_on_new_pass_on_construct&type=code