Copy Error: Start is offset by 256 in Vello

[DJMcNab]

Since 0.8.1 (i.e. with #79 fixed), I can't run wgpu-profiler on Vello, because of the:

[2024-09-12T10:10:03.568Z ERROR wgpu::backend::wgpu_core] Handling wgpu errors as fatal by default
thread 'main' panicked at /home/djmcnab/.cargo/registry/src/index.crates.io-6f17d22bba15001f/wgpu-22.1.0/src/backend/wgpu_core.rs:3411:5:
wgpu error: Validation Error

Caused by:
  In CommandEncoder::copy_buffer_to_buffer
    Copy error
      Copy of 256..544 would end up overrunning the bounds of the Destination buffer of size 288


stack backtrace:
   0: rust_begin_unwind
   1: core::panicking::panic_fmt
   2: core::ops::function::Fn::call
   3: wgpu::backend::wgpu_core::ContextWgpuCore::handle_error
   4: <wgpu::backend::wgpu_core::ContextWgpuCore as wgpu::context::Context>::command_encoder_copy_buffer_to_buffer
   5: <T as wgpu::context::DynContext>::command_encoder_copy_buffer_to_buffer
   6: wgpu::CommandEncoder::copy_buffer_to_buffer
   7: wgpu_profiler::profiler::GpuProfiler::resolve_queries
   8: vello::wgpu_engine::WgpuEngine::run_recording
   9: vello::Renderer::render_to_surface
  10: <with_winit::VelloApp as winit::application::ApplicationHandler<with_winit::UserEvent>>::window_event
  11: core::ops::function::impls::<impl core::ops::function::FnMut<A> for &mut F>::call_mut
  12: winit::platform_impl::platform::wayland::event_loop::EventLoop<T>::pump_events
  13: winit::platform_impl::platform::wayland::event_loop::EventLoop<T>::run_on_demand
  14: with_winit::main
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.

This can be reproduced in linebender/vello#687 using:

> cargo run -p with_winit

then pressing G

[Wumpf]

@DJMcNab thanks for the clean repro. Was able to get it into the regression test and fix it proper this time. Hopefully :).
Published 0.18.2 containing the fix!