OkHttpMethodBase: prevent NPE when logging exception

[AlvaroBrey]

Seen in Play Console crash reports

[AlvaroBrey]

/backport to stable-2.12

[github-actions]

SpotBugs (new)

Warning Type	Number
Bad practice Warnings	10
Correctness Warnings	35
Internationalization Warnings	6
Malicious code vulnerability Warnings	43
Multithreaded correctness Warnings	3
Performance Warnings	12
Security Warnings	1
Dodgy code Warnings	31
Total	141

SpotBugs (master)

Warning Type	Number
Bad practice Warnings	10
Correctness Warnings	35
Internationalization Warnings	6
Malicious code vulnerability Warnings	43
Multithreaded correctness Warnings	3
Performance Warnings	12
Security Warnings	1
Dodgy code Warnings	31
Total	141

[codecov]

Codecov Report

Merging #983 (a33586c) into master (f5d3dc3) will not change coverage.
The diff coverage is 0.00%.

Additional details and impacted files

@@           Coverage Diff           @@
##           master     #983   +/-   ##
=======================================
  Coverage   48.96%   48.96%           
=======================================
  Files         178      178           
  Lines        6678     6678           
  Branches      884      884           
=======================================
  Hits         3270     3270           
  Misses       2939     2939           
  Partials      469      469           

Impacted Files	Coverage Δ
...main/java/com/nextcloud/common/OkHttpMethodBase.kt	69.09% <0.00%> (ø)