; Replace error with signal in treesit.el

; Replace error with signal in treesit.el

(or (treesit-parser-create language)
    (error "Cannot find a parser for %s" language))

is turned into

(treesit-parser-create language)

because treesit-parser-create never returns nil.  (We used to use
treesit-get-parser which don't create parser automatically.)

* lisp/treesit.el (treesit-buffer-root-node): Replace error with signal.