Goal:
    P : E.t -> Prop  P_Proper : Proper (E.eq ==> impl) P  s : t
  ============================
   ((exists x : elt, InA E.eq x nil /\ P x) -> List.Exists P nil)


DEBUG:Going to execute:
inversion 1
Level 0: Backtrace:

In environment
P : E.t -> Prop
P_Proper : Proper (E.eq ==> impl) P
s : t
H : exists x : elt, InA E.eq x nil /\ P x
Unable to unify "List.Exists ?M2293 (?M2294 :: ?M2295)" with
 "List.Exists P nil".
Level 0: Backtrace:

In environment
P : E.t -> Prop
P_Proper : Proper (E.eq ==> impl) P
s : t
H : exists x : elt, InA E.eq x nil /\ P x
Unable to unify "List.Exists ?M2293 (?M2294 :: ?M2295)" with
 "List.Exists P nil".