worktree: don't return "untyped" negative numbers as error codes

src/worktree.c

@@ -234,37 +234,30 @@ void git_worktree_free(git_worktree *wt)
 
 int git_worktree_validate(const git_worktree *wt)
 {
-	int err = 0;
-
 	assert(wt);
 
 	if (!is_worktree_dir(wt->gitdir_path)) {
 		giterr_set(GITERR_WORKTREE,
 			"Worktree gitdir ('%s') is not valid",
 			wt->gitlink_path);
-		err = -1;
-		goto out;
+		return GIT_ERROR;
 	}
 
 	if (wt->parent_path && !git_path_exists(wt->parent_path)) {
 		giterr_set(GITERR_WORKTREE,
 			"Worktree parent directory ('%s') does not exist ",
 			wt->parent_path);
-		err = -2;
-		goto out;
+		return GIT_ERROR;
 	}
 
 	if (!git_path_exists(wt->commondir_path)) {
 		giterr_set(GITERR_WORKTREE,
 			"Worktree common directory ('%s') does not exist ",
 			wt->commondir_path);
-		err = -3;
-		goto out;
+		return GIT_ERROR;
 	}
 
-out:
-
-	return err;
+	return 0;
 }
 
 int git_worktree_add_init_options(git_worktree_add_options *opts,