I've done some investigation and concluded the only way you can get that error is if you copied the git-remote-nostr binary into your PATH as ngit.
I've released v1.5.2 which should fix your login issues.
nostr:nevent1qvzqqqqqqypzpgqgmmc409hm4xsdd74sf68a2uyf9pwel4g9mfdg8l5244t6x4jdqythwumn8ghj7un9d3shjtnwdaehgu3wvfskuep0qy88wumn8ghj7mn0wvhxcmmv9uqzp7whs6wplv59xxjmntdtjure94sgajuj5nmtlkj3we4talqgutrgnc7mkl