Fix NullPointer in DefaultConfig error logging

[lacikaaa]

We have seen this causing an issue when the Exception was missing a Cause.
The error logging is extended so we don't miss anything.
A bit of refactor to make it easily testable.

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 70.57%. Comparing base (857d56a) to head (80ca6f2).
⚠️ Report is 21 commits behind head on master.

Additional details and impacted files

@@             Coverage Diff              @@
##             master    #1039      +/-   ##
============================================
+ Coverage     70.43%   70.57%   +0.14%     
- Complexity     1542     1627      +85     
============================================
  Files           215      229      +14     
  Lines          7914     8306     +392     
  Branches        682      711      +29     
============================================
+ Hits           5574     5862     +288     
- Misses         1985     2073      +88     
- Partials        355      371      +16     

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