libknot/error: add a new error code -- KNOT_EEMPTYZONE

src/libknot/errcode.h

@@ -101,6 +101,7 @@ enum knot_error {
 	KNOT_EFD,
 	KNOT_ENOPARAM,
 	KNOT_EXPARAM,
+	KNOT_EEMPTYZONE,
 
 	KNOT_GENERAL_ERROR = -900,
 

src/libknot/error.c

@@ -100,6 +100,7 @@ static const struct error errors[] = {
 	{ KNOT_EFD,          "file descriptor error" },
 	{ KNOT_ENOPARAM,     "missing parameter" },
 	{ KNOT_EXPARAM,      "parameter conflict" },
+	{ KNOT_EEMPTYZONE,   "zone is empty" },
 
 	{ KNOT_GENERAL_ERROR, "unknown general error" },