refactor: Use null handling in SentryUIApplication.m

[philprime]

This PR is derived from #5572 in an effort to make the large amount of changes easier to review for #5577.

Resolves warnings in SentryUIApplication.m

#skip-changelog

[philprime]

cursor review

[cursor]

✅ Bugbot reviewed your changes and found no bugs!

---

[codecov]

Codecov Report

❌ Patch coverage is 7.69231% with 12 lines in your changes missing coverage. Please review.
✅ Project coverage is 86.676%. Comparing base (d720136) to head (ff38d5b).
⚠️ Report is 3 commits behind head on main.
✅ All tests successful. No failed tests found.

Files with missing lines	Patch %	Lines
Sources/Sentry/SentryUIApplication.m	7.692%	12 Missing ⚠️

Additional details and impacted files

@@              Coverage Diff              @@
##              main     #5886       +/-   ##
=============================================
- Coverage   86.681%   86.676%   -0.005%     
=============================================
  Files          423       423               
  Lines        36505     36508        +3     
  Branches     17273     17272        -1     
=============================================
+ Hits         31643     31644        +1     
  Misses        4817      4817               
- Partials        45        47        +2     

Files with missing lines	Coverage Δ
Sources/Sentry/SentryUIApplication.m	51.308% <7.692%> (-0.819%)	⬇️

... and 8 files with indirect coverage changes

---

Continue to review full report in Codecov by Sentry.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update d720136...ff38d5b. Read the comment docs.

[github-actions]

Performance metrics 🚀

	Plain	With Sentry	Diff
Startup time	1229.06 ms	1249.94 ms	20.88 ms
Size	23.75 KiB	919.62 KiB	895.87 KiB

Baseline results on branch: main

Startup times

Revision	Plain	With Sentry	Diff
ebc72be	1221.24 ms	1249.66 ms	28.42 ms
dad68ad	1229.15 ms	1261.98 ms	32.83 ms
aa0b738	1236.78 ms	1253.08 ms	16.31 ms
186f06f	1211.33 ms	1235.41 ms	24.08 ms
9be5373	1215.92 ms	1239.44 ms	23.52 ms
64c2b2b	1233.96 ms	1260.20 ms	26.24 ms
15c8cd5	1220.24 ms	1246.14 ms	25.90 ms
b41e6a7	1201.65 ms	1246.12 ms	44.47 ms
018037b	1209.31 ms	1228.33 ms	19.03 ms
7908e84	1224.33 ms	1246.39 ms	22.06 ms

App size

Revision	Plain	With Sentry	Diff
ebc72be	23.75 KiB	908.22 KiB	884.47 KiB
dad68ad	23.75 KiB	912.37 KiB	888.63 KiB
aa0b738	23.74 KiB	872.75 KiB	849.00 KiB
186f06f	23.75 KiB	876.94 KiB	853.19 KiB
9be5373	23.75 KiB	866.50 KiB	842.75 KiB
64c2b2b	23.75 KiB	908.55 KiB	884.80 KiB
15c8cd5	23.75 KiB	908.01 KiB	884.26 KiB
b41e6a7	23.75 KiB	908.03 KiB	884.28 KiB
018037b	23.75 KiB	867.16 KiB	843.41 KiB
7908e84	23.74 KiB	872.75 KiB	849.00 KiB

Previous results on branch: philprime/strict-nullability-1

Startup times

Revision	Plain	With Sentry	Diff
64bc73c	1219.28 ms	1248.39 ms	29.11 ms

App size

Revision	Plain	With Sentry	Diff
64bc73c	23.75 KiB	908.02 KiB	884.27 KiB

[philipphofmann]

Thanks