The draw() method was calling .pop() on next_frame.input_handlers to extract the active input handler for the platform window. This reduced the Vec length, making cached paint_range indices stale. On the next frame, when a cached view called reuse_paint(), it would index into rendered_frame.input_handlers with out-of-bounds indices, causing a panic: range start index 1 out of range for slice of length 0.

Fix: Use .last_mut().and_then(|h| h.take()) instead of .pop() to extract the handler without changing the Vec length. The slot becomes None, which is already handled by reuse_paint's .take() logic.

Closes #50456

Testing

• All 83 existing GPUI unit tests pass
• Manually verified with longbridge/gpui-component cargo run --example dock:
  • Switch to Input panel → type text → no crash ✅
  • Before fix: crash immediately on first keystroke

Before you mark this PR as ready for review, make sure that you have:

• Added a solid test coverage and/or screenshots from doing manual testing
• Done a self-review taking into account security and performance aspects
• Aligned any UI changes with the UI checklist (N/A — no UI changes)

Release Notes:

• Fixed a crash in GPUI when typing into an Input widget inside a cached view (#50456)