s "." throws execption Can't happen, feet are pre-processed.

[jwaldmann]

I am building https://github.com/jwaldmann/tidal-fuzz-test to aid testing for robustness. It found:

ghci -XOverloadedStrings
import Sound.Tidal.Context
s "."
*** Exception: Can't happen, feet are pre-processed.
CallStack (from HasCallStack):
  error, called at src/Sound/Tidal/ParseBP.hs:72:17 in tidal-1.4.9-3ae04c57a4310e0dfd8f893b003c5a06775a1692e5325314f45d21bfd22ca6f4:Sound.Tidal.ParseBP

I don't think there's much one can do: as long as the types are what they are, there's no good way to handle a parse error in parseBP_E, or a semantics error in toPat. In typical usage, this will just throw us to the next ghci prompt, which is what we want anyway.