The `onEnd()` callback is returning incorrect error information, specifically showing "Detail: 0."

Hi,

Thank you for your hard work in making this amazing bundler perfectly and efficiently.

Could you please look into why the `onEnd()` callback isn't handling errors properly? It only returns `text`, while everything else is omitted.

The same works as expected in onStart, onResolve and onLoad callbacks.

```ts
import * as esbuild from 'esbuild-wasm'

class CustomError extends Error {
detail: any
location: any
id: string
constructor(message: string) {
super(message)
this.name = 'CustomError'
this.detail = {
code: 'CUSTOM_CODE',
}
this.location = null
this.id = '123'
}
}

;(async () => {
await esbuild.initialize({
wasmURL: './node_modules/esbuild-wasm/esbuild.wasm',
})

try {
await esbuild.build({
stdin: {
contents: 'console.log(123)',
sourcefile: '/index.js',
resolveDir: '/',
},
plugins: [
{
name: 'test',
setup(build) {
build.onEnd(() => {
throw new CustomError('hello')
// Return {errors: [...]} // it will not work as well
})
},
},
],
})
} catch (err) {
console.log(JSON.stringify(err.errors, null, 2))
// Prints
/**
[
{
"id": "",
"pluginName": "test",
"text": "hello",
"location": null,
"notes": [],
"detail": 0
}
]
*/
}
})()

```

Start with the esbuild-wasm build.onEnd callback in the provided reproduction, then compare its error handling with onStart, onResolve, and onLoad. Run the example and inspect the resulting err.errors output; the issue is resolved when the onEnd error preserves fields such as detail, location, and id instead of returning detail 0.

Written by the indexing model from the issue text.