fix(pagination): handle empty page return case

Adds a check for empty pages in the pagination logic to return a 
nil slice and empty PageInfo when there are no items to display. 
Updates tests to verify the behavior when no more items are 
available, ensuring robustness in pagination functionality.

pagination.go

@@ -88,6 +88,9 @@ func GetPage[T any](items []T, first *int, after *string, last *int, before *str
 		eIx = idx
 	}
 	page := items[sIx:min(eIx, len(items))]
+	if len(page) == 0 {
+		return nil, PageInfo{}
+	}
 	return page, PageInfo{
 		StartCursor:     ptr(EncodeCursor(fn(page[0]))),
 		HasNextPage:     eIx < len(items),

pagination_test.go

@@ -45,6 +45,12 @@ func TestGetPage(t *testing.T) {
 				EndCursor:   ptr("Mg=="),
 			},
 		},
+		{
+			name:         "no more items",
+			args:         args[string]{items: []string{"1", "2", "3"}, first: ptr(2), after: ptr("Mw=="), max: 10, fn: func(s string) string { return s }},
+			wantItems:    nil,
+			wantPageInfo: PageInfo{},
+		},
 		{
 			name:      "first 10",
 			args:      args[string]{items: []string{"1", "2", "3"}, first: ptr(10), max: 10, fn: func(s string) string { return s }},