Fix panic when rendering thin textured rectangles (#5692)

* Closes https://github.com/emilk/egui/issues/5664
* [x] I have followed the instructions in the PR template

crates/epaint/src/tessellator.rs

@@ -1810,7 +1810,7 @@ impl Tessellator {
             }
         }
 
-        if stroke.is_empty() {
+        if stroke.is_empty() && out.texture_id == TextureId::default() {
             // Approximate thin rectangles with line segments.
             // This is important so that thin rectangles look good.
             if rect.width() <= 2.0 * self.feathering {