Empty message in announce script command (#4200)

Added a check to fail silently when the message in the *announce script commands is ""

src/map/intif.cpp

@@ -205,6 +205,10 @@ int intif_rename(struct map_session_data *sd, int type, char *name)
  */
 int intif_broadcast(const char* mes, int len, int type)
 {
+	nullpo_ret(mes);
+	if (len < 2)
+		return 0;
+
 	int lp = (type|BC_COLOR_MASK) ? 4 : 0;
 
 	// Send to the local players
@@ -246,6 +250,10 @@ int intif_broadcast(const char* mes, int len, int type)
  */
 int intif_broadcast2(const char* mes, int len, unsigned long fontColor, short fontType, short fontSize, short fontAlign, short fontY)
 {
+	nullpo_ret(mes);
+	if (len < 2)
+		return 0;
+
 	// Send to the local players
 	clif_broadcast2(NULL, mes, len, fontColor, fontType, fontSize, fontAlign, fontY, ALL_CLIENT);