Fix CAT meter parser crash on non-numeric rig replies

[patrickrb]

Root cause

The numeric CAT meter parsers validate the reply's token length but never that the substring is actually numeric before calling Integer.parseInt:

• Yaesu3Command.getALCOrSWR38 — parseInt(data.substring(1,4)) (FTDX/FT-950 family)
• Yaesu3Command.getSWROrALC39 — parseInt(data.substring(1,4)) (FT-891 family)
• Yaesu3Command.get590ALCOrSWR — parseInt(data.substring(1,5)) (Kenwood TS-590/2000/570) — also had no length guard at all
• ElecraftCommand.getSWRMeter — parseInt(data.substring(0,3))

These parsers run per-CAT-poll inside onReceiveData. On the Bluetooth SPP path the reply is dispatched to the parser on the main thread with no surrounding try/catch:

BluetoothSerialService.onSerialRead -> mainLooper.post
  -> BluetoothRigConnector.onSerialRead -> onData
  -> BaseRig.onReceiveData -> <Rig>.onReceiveData -> Yaesu3Command/ElecraftCommand

So a garbled or non-numeric meter reply from the rig threw NumberFormatException (or StringIndexOutOfBoundsException for the unguarded get590ALCOrSWR) and hard-crashed the app. (The USB path is caught by SerialInputOutputManager.run(), which only tears down the CAT thread — hence this bites Bluetooth-connected rigs.)

Fix

Treat malformed meter data as "no reading" (return 0) instead of throwing, matching the existing getFrequency() convention already used in the same two files. Added a length guard to get590ALCOrSWR to match its sibling parsers.

0 is the safe sentinel: it never falsely trips the SWR-halt / ALC auto-volume protection (MeterProtectionController), which key off high values.

Testing

• New CatMeterParserTest covers numeric, non-numeric, and short data for all four parsers (12 cases). Verified the 6 malformed-data cases fail with NumberFormatException/StringIndexOutOfBoundsException against the old code, and all 12 pass after the fix.
• Full :app:testDebugUnitTest suite passes.
• :app:assembleDebug (including native build) succeeds.

Risk

Very low. Behavior is unchanged for valid meter replies (same parsed integer); only malformed/garbled input changes from crash to 0. No protocol, DSP, or threading behavior touched. No device was attached in this environment, so no on-device verification was performed.

🤖 Generated with Claude Code

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 23.35%. Comparing base (d71f162) to head (d319bdd).

Additional details and impacted files

@@            Coverage Diff            @@
##                dev     #489   +/-   ##
=========================================
  Coverage     23.34%   23.35%           
- Complexity      149      162   +13     
=========================================
  Files           165      167    +2     
  Lines         21401    21450   +49     
  Branches       3149     3154    +5     
=========================================
+ Hits           4997     5009   +12     
- Misses        16215    16248   +33     
- Partials        189      193    +4     

Flag	Coverage Δ
android	13.26% <ø> (+0.03%)	⬆️
native	9.93% <ø> (ø)

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[Copilot]

Pull request overview

This pull request hardens CAT meter parsing against malformed rig replies to prevent main-thread crashes (notably on the Bluetooth SPP path), while preserving behavior for valid numeric meter data.

Changes:

• Add numeric parsing guards (length checks + NumberFormatException handling) for Yaesu/Kenwood meter parsers in Yaesu3Command.
• Add length check + NumberFormatException handling for Elecraft SWR meter parsing in ElecraftCommand.
• Introduce a new unit test suite (CatMeterParserTest) covering valid, non-numeric, and short meter replies across the affected parsers.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.

File	Description
ft8af/app/src/main/java/com/k1af/ft8af/rigs/Yaesu3Command.java	Prevents crashes by guarding substring bounds and safely parsing meter tokens via a shared helper that returns 0 on malformed input.
ft8af/app/src/main/java/com/k1af/ft8af/rigs/ElecraftCommand.java	Adds length check and safe parsing to avoid NumberFormatException crashes on malformed SWR replies.
ft8af/app/src/test/java/com/k1af/ft8af/rigs/CatMeterParserTest.java	Adds focused unit coverage for all affected meter parsers across valid and malformed inputs.

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