After that, as I scroll through my init.el, the Messages buffer is getting flooded with errors like these:

Error during redisplay: (jit-lock-function 2501) signaled (invalid-regexp "Unmatched ) or \\)")

Error during redisplay: (jit-lock-function 3001) signaled (invalid-regexp "Unmatched ) or \\)")

Error during redisplay: (jit-lock-function 3501) signaled (invalid-regexp "Unmatched ) or \\)")

Error during redisplay: (jit-lock-function 4001) signaled (invalid-regexp "Unmatched ) or \\)")

Error during redisplay: (jit-lock-function 4501) signaled (invalid-regexp "Unmatched ) or \\)")

Error during redisplay: (jit-lock-function 5001) signaled (invalid-regexp "Unmatched ) or \\)")

Error during redisplay: (jit-lock-function 5501) signaled (invalid-regexp "Unmatched ) or \\)")

Error during redisplay: (jit-lock-function 6001) signaled (invalid-regexp "Unmatched ) or \\)")

Error during redisplay: (jit-lock-function 6501) signaled (invalid-regexp "Unmatched ) or \\)")

Error during redisplay: (jit-lock-function 7001) signaled (invalid-regexp "Unmatched ) or \\)")

Error during redisplay: (jit-lock-function 7501) signaled (invalid-regexp "Unmatched ) or \\)")

Error during redisplay: (jit-lock-function 8001) signaled (invalid-regexp "Unmatched ) or \\)")

Error during redisplay: (jit-lock-function 8501) signaled (invalid-regexp "Unmatched ) or \\)")

Error during redisplay: (jit-lock-function 9001) signaled (invalid-regexp "Unmatched ) or \\)")

Error during redisplay: (jit-lock-function 9501) signaled (invalid-regexp "Unmatched ) or \\)")

Error during redisplay: (jit-lock-function 10001) signaled (invalid-regexp "Unmatched ) or \\)")

Error during redisplay: (jit-lock-function 10501) signaled (invalid-regexp "Unmatched ) or \\)")

Error during redisplay: (jit-lock-function 11001) signaled (invalid-regexp "Unmatched ) or \\)")

Error during redisplay: (jit-lock-function 11501) signaled (invalid-regexp "Unmatched ) or \\)")