message: Fix uninitialized mailbox error
diff: @@ -96,7 +96,7 @@ uint32_t ODriveCAN::write(CAN_message_t &txmsg) {
  header.DLC = txmsg.len;
  header.TransmitGlobalTime = FunctionalState::DISABLE;
  - uint32_t retTxMailbox;
  + uint32_t retTxMailbox = 0;
  if (HAL_CAN_GetTxMailboxesFreeLevel(handle_) > 0)
  HAL_CAN_AddTxMessage(handle_, &header, txmsg.buf, &retTxMailbox);
  