DefaultController: catch oauth exceptions during login

[agoujot]

Nothing else to say?

[codecov]

Codecov Report

❌ Patch coverage is 0% with 9 lines in your changes missing coverage. Please review.
✅ Project coverage is 69.62%. Comparing base (4b8eb28) to head (9154a81).
⚠️ Report is 188 commits behind head on main.

Files with missing lines	Patch %	Lines
src/Controller/DefaultController.php	0.00%	9 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##               main     #580      +/-   ##
============================================
- Coverage     71.30%   69.62%   -1.69%     
- Complexity     1275     1323      +48     
============================================
  Files            46       46              
  Lines          3792     3977     +185     
============================================
+ Hits           2704     2769      +65     
- Misses         1088     1208     +120     

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[agoujot]

D'you mind taking a look? We've been getting quite many failmails about this.