[stable12] If for some reason the json can't be decoded it is not cached

[MorrisJobke]

Should fix #6898

Backport of #7109

👍 from me

[codecov]

Codecov Report

Merging #7118 into stable12 will decrease coverage by 2.8%.
The diff coverage is 50%.

@@              Coverage Diff               @@
##             stable12    #7118      +/-   ##
==============================================
- Coverage       56.55%   53.75%   -2.81%     
- Complexity      21053    22586    +1533     
==============================================
  Files            1289     1384      +95     
  Lines           79449    86657    +7208     
  Branches         1329     1329              
==============================================
+ Hits            44935    46583    +1648     
- Misses          34514    40074    +5560

Impacted Files	Coverage Δ	Complexity Δ
lib/private/Template/JSCombiner.php	88.63% <50%> (-0.9%)	25 <0> (+1)
apps/sharebymail/tests/SettingsTest.php	52.17% <0%> (-47.83%)	3% <0%> (ø)
lib/private/Security/RateLimiting/Limiter.php	55.55% <0%> (-44.45%)	5% <0%> (ø)
settings/Controller/EncryptionController.php	56% <0%> (-37.34%)	8% <0%> (ø)
settings/Controller/GroupsController.php	64.61% <0%> (-35.39%)	9% <0%> (ø)
lib/public/API.php	66.66% <0%> (-33.34%)	1% <0%> (ø)
...ps/comments/tests/Unit/AppInfo/ApplicationTest.php	69.56% <0%> (-30.44%)	4% <0%> (ø)
apps/user_ldap/lib/Configuration.php	41.5% <0%> (-29.46%)	86% <0%> (ø)
apps/encryption/lib/Command/EnableMasterKey.php	75% <0%> (-25%)	5% <0%> (ø)
lib/private/AvatarManager.php	61.9% <0%> (-24.77%)	4% <0%> (ø)
... and 269 more