Fix NoneType AttributeError in firefox extension plugin

[M1ra1B0T]

This PR fixes a NoneType AttributeError in the firefox extension plugin.
When parsing the firefox extension information from the json file, we use the dictionary get method to access the relevant key value pairs. However, I ran into an uncatched NoneType AttributeError if the original key value is None, but we expect a nested dictionary, e.g. for the "name" field.

Additionally, the error message was slightly adapted, so instead of logging the whole user object, it now only prints the username as it should.

[Schamper]

Do you have some test data or could you add some data to the unit test for this? Maybe I'm missing something but on first glance the previous code should be functionality identical?

In [1]: extension = {}

In [2]: repr(extension.get("defaultLocale", {}).get("name"))
Out[2]: 'None'

In [3]: extension = {"defaultLocale": {}}

In [4]: repr(extension.get("defaultLocale", {}).get("name"))
Out[4]: 'None'

[M1ra1B0T]

@Schamper The error occurs if the field defaultLocale is actually None or null

>>> extension = {"defaultLocale": None}
>>> repr(extension.get("defaultLocale", {}).get("name"))
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
AttributeError: 'NoneType' object has no attribute 'get'

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 75.05%. Comparing base (f999b3a) to head (40fee57).

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #713   +/-   ##
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  Coverage   75.05%   75.05%           
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  Files         295      295           
  Lines       25084    25084           
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  Hits        18827    18827           
  Misses       6257     6257           

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[Schamper]

Suggested something a bit more concise.

[Schamper]

Thanks! Was actually running into this issue too while working on another feature.