message: Unbreak nucleo build.
  This wasn't running in CI yet, but I'm about to add it.
  GPC: unbreak-nucleo
diff: @@ -441,6 +441,13 @@ inline uint16_t HalApi::serialBytesAvailableForWrite() {
  return Serial.availableForWrite();
  }
  +// No implementation of debugRead/Write on Nucleo because the Arduino API
  +// doesn't expose a separate debug serial port.
  +inline uint16_t HalApi::debugWrite(const char *buf, uint16_t len) {
  + return len;
  +}
  +inline uint16_t HalApi::debugRead(char *buf, uint16_t len) { return 0; }
  +
  inline void HalApi::watchdog_init() {
  // Our only user of the Arduino API is Nucleo, i.e. STM32 using Arduino APIs.
  // Unfortunately it does not expose the watchdog API, so we can't implement
  