Simple bug in xref-backend-definitions leads to error when using `xref-find-definitions` key binding.

[JoshLitt]

There is a bug in these lines. Maybe responsible for #171 (though that issue doesn't seem to describe the context where it's seen)

https://github.com/mopemope/meghanada-emacs/blob/1e41f7f2c7a172e9699f3557c97c3f39a149bfc2/meghanada.el#L1887-L1899

The (message "client connection not established") at the end of xref-backend-definitions is part of the THEN clause of the if, but it should be the else clause.