fix(radio): replace beginSending() asserts with graceful rejection

[ndoo]

Problem

RadioInterface::beginSending() guards four invariants with assert(): no send already in progress, payload already encrypted, sender node num set, and encrypted payload fits the radio buffer. On STM32WL these all hang forever with no diagnostic instead of dropping the one bad packet (__wrap___assert_func is while(true);).

Fix

Convert each assert() to a checked early return: log, release p, return 0. Both callers (RadioLibInterface::startSend(), SimRadio::startSend()) are updated to check for a 0 return and bail out cleanly instead of proceeding to transmit/use the now-released packet.

Test plan

• pio run -e wio-e5 / pio run -e rak3172 / pio run -e native-macos — build clean (native-macos exercises the SimRadio.cpp caller).
• Hardware (wio-e5): flashed, confirmed clean boot, sent a text message over LoRa and confirmed the device stays responsive — exercises the normal (non-failing) path through the new checks.
• The four specific invariant violations weren't independently reproduced live (they require corrupting internal router state to trigger) — this is a mechanical assert→checked-return conversion, same pattern as fix(router): release packets Router::send() declines instead of leaking them #11231/fix(mesh): harden MemoryPool<T,MaxSize>::release() against bad pointers #11232.

🤝 Attestations

• I have tested that my proposed changes behave as described.
• I have tested that my proposed changes do not cause any obvious regressions on the following devices:
  • Heltec (Lora32) V3
  • LilyGo T-Deck
  • LilyGo T-Beam
  • RAK WisBlock 4631
  • Seeed Studio T-1000E tracker card
  • Other (please specify below): wio-e5 — build + hardware verified per test plan above. rak3172 build-verified only.

[coderabbitai]

Important

Review skipped

Draft detected.

Please check the settings in the CodeRabbit UI or the .coderabbit.yaml file in this repository. To trigger a single review, invoke the @coderabbitai review command.

⚙️ Run configuration

Configuration used: Path: .coderabbit.yaml

Review profile: CHILL

Plan: Pro Plus

Run ID: 1e3375d3-587b-4c22-9195-7df9b40e4cf4

You can disable this status message by setting the reviews.review_status to false in the CodeRabbit configuration file.

Use the checkbox below for a quick retry:

• 🔍 Trigger review

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

---

Thanks for using CodeRabbit! It's free for OSS, and your support helps us grow. If you like it, consider giving us a shout-out.

❤️ Share

• X
• Mastodon
• Reddit
• LinkedIn

_{Comment @coderabbitai help to get the list of available commands.}

[github-actions]

⚡ Try this PR in the Web Flasher

Note

Building this pull request… the flash button, badges and supported-board
list will appear here automatically once CI finishes.

[ndoo]

Closing — this is superseded by @t-miura's #11223 (the RadioInterface.cpp/RadioLibInterface.cpp portions — null/size/variant checks in beginSending() and the numbytes==0 handling in startSend()) and #11229 (the SimRadio.cpp portion, which handles the same numbytes==0 case more thoroughly than this PR did — it changes startSend()'s signature to propagate success/failure back to onNotify() rather than just early-returning). Both were opened before this one. Thanks for the more complete fix!