For icom recognize bad command return packets e.g. fe fe e0 50 fa fd

https://github.com/Hamlib/Hamlib/issues/607

rigs/icom/frame.c

@@ -279,6 +279,9 @@ int icom_one_transaction(RIG *rig, int cmd, int subcmd,
     }
 
     if (frm_len < ACKFRMLEN) { RETURNFUNC(-RIG_EPROTO); }
+    // if we send a bad command we will get back a NAK packet
+    // e.g. fe fe e0 50 fa fd
+    if (NAK == buf[frm_len - 2]) { RETURNFUNC(-RIG_ERJCTED); }
 
     rig_debug(RIG_DEBUG_TRACE, "%s: frm_len=%d, frm_len-1=%02x, frm_len-2=%02x\n", __func__, frm_len, buf[frm_len-1], buf[frm_len-2]);
 

rigs/icom/icom.h

@@ -30,7 +30,7 @@
 #include <sys/time.h>
 #endif
 
-#define BACKEND_VER "20210310"
+#define BACKEND_VER "20210313"
 
 /*
  * defines used by comp_cal_str in rig.c