Case split causes my function to no longer be covering

[FFFluoride]

Gist with minimal example

Steps to Reproduce

Case split on prf here

Expected Behavior

Case splits and decideWord is still covering after reloading.

Observed Behavior

decideWord is no longer covering

Error for reference:

- + Errors (1)
 `-- src/Test.idr line 9 col 0:
     decideWord is not covering.
     
     Test:9:1--9:80
      5 | 
      6 | data WordValidInput : Type -> Type where
      7 |   MkWordValidInput : (word : List Char) -> WordValidInput (Elem ' ' word -> Void)
      8 | 
      9 | decideWord : (word : List Char) -> Dec (WordValidInput (Elem ' ' word -> Void))
          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
     
     Calls non covering function Test.case block in decideWord