i get this error

File mode specification error: (file-missing Cannot open load file No such file or directory cider-compat) 

when i run cider-jack-in-cljs in a .cljc file. To be clear, given this is /emacs i'm not asking about this specific error but how to debug in general. How do i get a stack trace? Or get some sense how this error message was put together?

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[edit] mostly solved. ty