Fix missing key error and update heading when using external gps.

[ltindall]

No description provided.

[codecov]

Codecov Report

Attention: 6 lines in your changes are missing coverage. Please review.

Comparison is base (81f65d4) 75.63% compared to head (7d9a3ad) 75.55%.
Report is 3 commits behind head on main.

Files	Patch %	Lines
gamutrf/mqtt_reporter.py	0.00%	6 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1171      +/-   ##
==========================================
- Coverage   75.63%   75.55%   -0.09%     
==========================================
  Files          39       39              
  Lines        3714     3718       +4     
==========================================
  Hits         2809     2809              
- Misses        905      909       +4     

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