Fix build break

src/nnn.c

@@ -4367,6 +4367,8 @@ static int dentfill(char *path, struct entry **dents)
 		num_files = 0;
 		dir_blocks = 0;
 		buf = (char *)alloca(strlen(path) + NAME_MAX + 2);
+		if (!buf)
+			return 0;
 
 		if (fstatat(fd, path, &sb_path, 0) == -1)
 			goto exit;