Fix PropertyList infinity loop for LabeledContent demo

[Kyle-Ye]

No description provided.

[codecov]

Codecov Report

❌ Patch coverage is 33.33333% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 24.44%. Comparing base (377b2e0) to head (2d71cb4).
⚠️ Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
...urces/OpenSwiftUICore/Data/Util/PropertyList.swift	33.33%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #561      +/-   ##
==========================================
- Coverage   24.46%   24.44%   -0.03%     
==========================================
  Files         513      513              
  Lines       29425    29425              
==========================================
- Hits         7200     7193       -7     
- Misses      22225    22232       +7     

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