This follows the same convention of M/G codes, so that the user knowns that the D-code has been either handled or ignored.
@@ -9521,6 +9521,9 @@ Sigma_Exit:
#endif //FILAMENT_SENSOR
#endif //DEBUG_DCODES
+
+ default:
+ printf_P(PSTR("Unknown D code: %s\n"), cmdbuffer + bufindr + CMDHDRSIZE);
}