WebGPU backend: "Cannot perform %TypedArray%.prototype.set on a detached ArrayBuffer" if buffer is destroyed

[kpreid]

Description

Map a buffer for reading (update after #7007: must map for writing and actually write, instead), then destroy() it before dropping its BufferView, and get this error:

wasm-bindgen: imported JS function that was not marked as `catch` threw an error:
Cannot perform %TypedArray%.prototype.set on a detached ArrayBuffer

Stack:
TypeError: Cannot perform %TypedArray%.prototype.set on a detached ArrayBuffer
    at Uint8Array.set (<anonymous>)
    at http://127.0.0.1:49227/wasm-bindgen-test:2772:25
    at logError (http://127.0.0.1:49227/wasm-bindgen-test:242:18)
    at imports.wbg.__wbg_set_a47bac70306a19a7 (http://127.0.0.1:49227/wasm-bindgen-test:2771:66)
    at browser-f9157397fa96c579.wasm.js_sys::Uint8Array::set::h93600a3ef01210e9 (http://127.0.0.1:49227/wasm-bindgen-test_bg.wasm:wasm-function[16282]:0x878474)
    at browser-f9157397fa96c579.wasm.<wgpu::backend::webgpu::BufferMappedRange as core::ops::drop::Drop>::drop::h68cdd1b1ee07437b (http://127.0.0.1:49227/wasm-bindgen-test_bg.wasm:wasm-function[10012]:0x7fca51)
    at browser-f9157397fa96c579.wasm.core::ptr::drop_in_place<wgpu::backend::webgpu::BufferMappedRange>::hadbe2842852a0293 (http://127.0.0.1:49227/wasm-bindgen-test_bg.wasm:wasm-function[10624]:0x815f77)

There are two problems here:

1. This should either succeed or be a wgpu validation error.
2. Why is it even trying to write back, when the mapping was for reading? That's not a bug, but it's certainly an inefficiency. Fixed by Don’t copy buffer data back to JS if unnecessary, in WebGPU backend. #7007

Platform

wgpu version: 22.1.0
Browser version: Chrome 128.0.6613.113 (macOS)