Ensure script to run is not a directory

src/nnn.c

@@ -3404,12 +3404,17 @@ nochange:
 						tmp = newpath;
 					}
 
-					/* Check if file exists */
-					if (access(tmp, F_OK) == -1) {
+					if (lstat(tmp, &sb) == -1) {
 						printwarn();
 						goto nochange;
 					}
 
+					/* Check if it's a directory */
+					if (S_ISDIR(sb.st_mode)) {
+						printmsg("directory");
+						goto nochange;
+					}
+
 					dir = NULL; /* dir used as temp var */
 					if (ndents)
 						dir = dents[cur].name;