Fix notification: --all dont relay on a repo (#159)

fix nil pointer exeption

make notifications work outside a repo

Co-authored-by: 6543 <6543@obermui.de>
Reviewed-on: https://gitea.com/gitea/tea/pulls/159
Reviewed-by: Lunny Xiao <xiaolunwen@gmail.com>
Reviewed-by: mrsdizzie <info@mrsdizzie.com>

cmd/config.go

@@ -197,6 +197,9 @@ func curGitRepoPath(path string) (*Login, string, error) {
 	} else {
 		repo, err = git.RepoFromPath(path)
 	}
+	if err != nil {
+		return nil, "", err
+	}
 	gitConfig, err := repo.Config()
 	if err != nil {
 		return nil, "", err