fix: Rare battery breadcrumbs crash

[philipphofmann]

📜 Description

We see rare crashes in getBatteryStatus of SentrySystemEventBreadcrumbs. The object of an NSNotification can be nil, and we didn't check for that edge case. This PR fixes that problem and uses dictionaryWithCapacity to slightly reduce the memory footprint for getBatteryStatus. This change is not guaranteed to fix these rare crashes, but it won't do any harm.

Internal SDK crashes

💡 Motivation and Context

Came up while investigating #3341.

💚 How did you test it?

Unit testing.

📝 Checklist

You have to check all boxes before merging:

• I reviewed the submitted code.
• I added tests to verify the changes.
• No new PII added or SDK only sends newly added PII if sendDefaultPII is enabled.
• I updated the docs if needed.
• Review from the native team if needed.
• No breaking change or entry added to the changelog.
• No breaking change for hybrid SDKs or communicated to hybrid SDKs.

🔮 Next steps

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (eef4553) 89.285% compared to head (ce54466) 89.289%.
Report is 2 commits behind head on main.

Additional details and impacted files

@@              Coverage Diff              @@
##              main     #3582       +/-   ##
=============================================
+ Coverage   89.285%   89.289%   +0.003%     
=============================================
  Files          529       529               
  Lines        57753     57764       +11     
  Branches     20670     20673        +3     
=============================================
+ Hits         51565     51577       +12     
- Misses        5277      5281        +4     
+ Partials       911       906        -5     

Files	Coverage Δ
Sources/Sentry/SentrySystemEventBreadcrumbs.m	100.000% <100.000%> (ø)
...Breadcrumbs/SentrySystemEventBreadcrumbsTest.swift	98.062% <100.000%> (+0.070%)	⬆️

... and 14 files with indirect coverage changes

---

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[github-actions]

Performance metrics 🚀

	Plain	With Sentry	Diff
Startup time	1212.12 ms	1221.49 ms	9.37 ms
Size	21.58 KiB	418.14 KiB	396.56 KiB

Baseline results on branch: main

Startup times

Revision	Plain	With Sentry	Diff
e324230	1225.84 ms	1250.40 ms	24.57 ms
31208ed	1258.36 ms	1263.86 ms	5.50 ms
16450b8	1196.33 ms	1217.26 ms	20.93 ms
56ec5d0	1194.39 ms	1236.94 ms	42.55 ms
7cd187e	1229.02 ms	1233.06 ms	4.04 ms
407ff99	1190.89 ms	1237.18 ms	46.29 ms
d413317	1203.27 ms	1215.02 ms	11.75 ms
881a955	1242.24 ms	1247.85 ms	5.61 ms
98cca71	1226.66 ms	1242.94 ms	16.28 ms
b9a9ffd	1221.18 ms	1235.37 ms	14.19 ms

App size

Revision	Plain	With Sentry	Diff
e324230	22.85 KiB	408.87 KiB	386.02 KiB
31208ed	20.76 KiB	435.26 KiB	414.50 KiB
16450b8	22.85 KiB	410.98 KiB	388.13 KiB
56ec5d0	20.76 KiB	414.44 KiB	393.68 KiB
7cd187e	20.76 KiB	401.65 KiB	380.89 KiB
407ff99	20.76 KiB	427.86 KiB	407.10 KiB
d413317	20.76 KiB	420.71 KiB	399.95 KiB
881a955	22.85 KiB	407.63 KiB	384.78 KiB
98cca71	22.85 KiB	411.14 KiB	388.29 KiB
b9a9ffd	21.58 KiB	418.43 KiB	396.85 KiB

Previous results on branch: fix/battery-notification-nil-check

Startup times

Revision	Plain	With Sentry	Diff
33e820d	1210.41 ms	1231.75 ms	21.34 ms
ae790ff	1241.92 ms	1261.14 ms	19.22 ms

App size

Revision	Plain	With Sentry	Diff
33e820d	21.58 KiB	417.94 KiB	396.36 KiB
ae790ff	21.58 KiB	418.00 KiB	396.42 KiB

[kahest]

LGTM, just one small suggestion

thx for the good PR description and the opportunistic refactor 👍