charAt is throwing out of bounds, if empty string

[tobiasKaminsky]

This was overseen by us at #3070

Signed-off-by: tobiasKaminsky tobias@kaminsky.me

[AndyScherzinger]

@tobiasKaminsky I added the length check in 2 more classes 4612f0e
This is rather for bullet proofing the code since I would say in these cases the string should never be empty.

[codecov]

Codecov Report

Merging #3090 into master will decrease coverage by <.01%.
The diff coverage is 0%.

@@             Coverage Diff             @@
##             master   #3090      +/-   ##
===========================================
- Coverage      6.48%   6.48%   -0.01%     
  Complexity        1       1              
===========================================
  Files           307     307              
  Lines         30084   30084              
  Branches       4316    4316              
===========================================
- Hits           1952    1950       -2     
  Misses        27840   27840              
- Partials        292     294       +2

Impacted Files	Coverage Δ	Complexity Δ
.../java/com/owncloud/android/utils/DisplayUtils.java	5.74% <0%> (ø)	0 <0> (ø)	⬇️
...ge/providers/MountCommandStoragePointProvider.java	16.66% <0%> (ø)	0 <0> (ø)	⬇️
...in/java/com/owncloud/android/datamodel/OCFile.java	63.81% <0%> (ø)	0 <0> (ø)	⬇️
.../third_parties/daveKoeller/AlphanumComparator.java	79.76% <0%> (-2.39%)	0% <0%> (ø)

[AndyScherzinger]

👍 from my side

@tobiasKaminsky please have a look at my commit #3090 (comment) and feel free to merge if you are fine with the change :)

[nextcloud-android-bot]

Lint

Type	Master	PR
Warnings	113	113
Errors

FindBugs (new)

Warning Type	Number
Bad practice Warnings	35
Correctness Warnings	167
Internationalization Warnings	14
Malicious code vulnerability Warnings	10
Multithreaded correctness Warnings	9
Performance Warnings	124
Security Warnings	203
Dodgy code Warnings	139
Total	701

FindBugs (master)

Warning Type	Number
Bad practice Warnings	35
Correctness Warnings	167
Internationalization Warnings	14
Malicious code vulnerability Warnings	10
Multithreaded correctness Warnings	9
Performance Warnings	124
Security Warnings	203
Dodgy code Warnings	139
Total	701