Simplify MapError implementation

Author: BooleanCat

it/map.go

@@ -31,14 +31,8 @@ func Map2[V, W, X, Y any](delegate func(func(V, W) bool), f func(V, W) (X, Y)) i
 func MapError[V, W any](delegate func(func(V) bool), f func(V) (W, error)) iter.Seq2[W, error] {
 	return func(yield func(W, error) bool) {
 		for value := range delegate {
-			if result, err := f(value); err != nil {
-				if !yield(result, err) {
-					return
-				}
-			} else {
-				if !yield(result, nil) {
-					return
-				}
+			if !yield(f(value)) {
+				return
 			}
 		}
 	}