This worked for me too! For anyone running into this issue, use this command
rm -rf ~/.cursor/ms-vscode-remote.remote-ssh-0.113.1 then reinstall the extension
For google searches to find this, the errors I had were
“command ‘opensshremotes.openEmptyWindow’ not found”
As well as “ms-vscode-remote.remote-ssh’ failed: Unexpected end of input.” in developer tools