Bug report: recent commit of `eglot-x` breaks `xref-go-back`

[roife]

Hi! Thank you for your contributions to this project. This package has greatly helped me in debugging rust-analyzer on Emacs.

However, recently I encountered an issue after from the commit a7994d19f4f98ba8d943ee4c55c5082ec2d8b82f where Emacs frequently reports the following error:

eglot-x--run-after-jump: [eglot-x] Server sent an unknown Runnable kind: nil

This error makes xref-go-back unusable. I suspect it might be a bug in eglot-x. Could you please look into it?

[nemethf]

The report does not say how the issue can be reproduced, so it is hard to understand the underlying problem, but I fixed something.