path: short-circuit `git_path_apply_relative` on error

Short-circuit the call to `git_path_resolve_relative` in case
`git_buf_joinpath` returns an error. While this does not fix any
immediate errors, the resulting code is easier to read and handles
potential new error conditions raised by `git_buf_joinpath`.

src/path.c

@@ -826,8 +826,8 @@ int git_path_resolve_relative(git_buf *path, size_t ceiling)
 
 int git_path_apply_relative(git_buf *target, const char *relpath)
 {
-	git_buf_joinpath(target, git_buf_cstr(target), relpath);
-	return git_path_resolve_relative(target, 0);
+	return git_buf_joinpath(target, git_buf_cstr(target), relpath) ||
+	    git_path_resolve_relative(target, 0);
 }
 
 int git_path_cmp(