simplify cast_resolved

src/rstd/cast.rs

@@ -188,13 +188,11 @@ fn cast_resolved<'a, Ctx: CastCtx<'a>, A: Mentionable<'a, Ctx>>(
     resolved: ResolutionResult<'a, Ctx, TypelessMentionable<'a, Ctx>>,
     factory: A::Fctr,
 ) -> ResolutionResult<'a, Ctx, A> {
-    match resolved {
-        Ok(typeless_mentionable) => match typeless_mentionable.cast(factory) {
-            Ok(mentionable) => Ok(Rc::new(mentionable)),
-            Err(parse_error) => Err(ResolutionError::Parse(parse_error)),
-        },
-        Err(error) => Err(cast_error::<Ctx, A>(error)),
-    }
+    resolved
+        .map_err(cast_error::<Ctx, A>)?
+        .cast(factory)
+        .map_err(ResolutionError::Parse)
+        .map(Rc::new)
 }
 
 fn cast_resolve<'a, Ctx: CastCtx<'a>, A: Mentionable<'a, Ctx>>(