@react-navigation/stack libdef: Simplify setParams a bit.

As it says in the comment, Flow has some trouble with the more
complex type in types-first mode. It would give some wrong-looking
errors:

Error ┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈ flow-typed/@react-navigation/stack_v5.x.x.js:844:22

object type [1] is incompatible with undefined [2] in the first argument. [incompatible-type]

     flow-typed/@react-navigation/stack_v5.x.x.js
 [2] 420│   declare type $IsUndefined<X> = $IsA<X, void>;
        :
     841│     +setOptions: (options: $Shape<ScreenOptions>) => void,
     842│     +setParams: (
     843│       params: $If<
     844│         $IsUndefined<$ElementType<ParamList, RouteName>>,
     845│         empty,
     846│         $Shape<$NonMaybeType<$ElementType<ParamList, RouteName>>>,
     847│       >,

     src/nav/AppNavigator.js
 [1]  53│   chat: RouteParamsOf<typeof ChatScreen>,

Error ┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈ src/chat/ChatScreen.js:113:57

Cannot call navigation.setParams with object literal bound to params because object literal [1] is incompatible with
empty [2]. [incompatible-call]

     src/chat/ChatScreen.js
     110│
     111│   const { narrow, editMessage } = route.params;
     112│   const setEditMessage = useCallback(
 [1] 113│     (value: EditMessage | null) => navigation.setParams({ editMessage: value }),
     114│     [navigation],
     115│   );
     116│

     flow-typed/@react-navigation/stack_v5.x.x.js
 [2] 843│       params: $If<
     844│         $IsUndefined<$ElementType<ParamList, RouteName>>,
     845│         empty,
     846│         $Shape<$NonMaybeType<$ElementType<ParamList, RouteName>>>,
     847│       >,

Author: chrisbobbe

flow-typed/@react-navigation/stack_v5.x.x.js

@@ -840,11 +840,15 @@ declare module '@react-navigation/stack' {
     >>,
     +setOptions: (options: $Shape<ScreenOptions>) => void,
     +setParams: (
-      params: $If<
-        $IsUndefined<$ElementType<ParamList, RouteName>>,
-        empty,
-        $Shape<$NonMaybeType<$ElementType<ParamList, RouteName>>>,
-      >,
+      // We've edited this to be less complicated, so Flow in types-first
+      // mode can handle it.
+      //
+      // A slight downside of the edit is that the more complicated thing
+      // used to error when you tried to use `setParams` on a screen whose
+      // type says it has no params. Now we don't get those errors.
+      // Hopefully that kind of error is easy enough to avoid without help
+      // from the type-checker though.
+      params: $Shape<$NonMaybeType<$ElementType<ParamList, RouteName>>>,
     ) => void,
     ...
   };