Cannot read properties of undefined (reading 'terminate')

[YOUR1]

Whenever I try the browser-version with a simple class:

import * as xmllint from "xmllint-wasm/index-browser";

export class ModelValidator {
    constructor(private xml: string) {}

    private async getSchema(): Promise<string> {
        const response = await fetch(Model.xsd');
        return await response.text()
    }

    async process(callback: any) {
        xmllint.memoryPages
        const { valid, rawOutput, normalized } = await xmllint.validateXML({
            xml: { fileName: 'model.xml', contents: this.xml },
            schema: await this.getSchema(),
            normalization: 'format'
        });
        callback(valid, rawOutput, normalized);
    }

}

I get the following error:

ModelValidator.ts:9 ERROR Error: Uncaught (in promise): TypeError: Cannot read properties of undefined (reading 'terminate')
TypeError: Cannot read properties of undefined (reading 'terminate')
    at index-browser.mjs:165:26
    at _ZoneDelegate.invoke (zone.js:368:26)
    at Object.onInvoke (core.mjs:27450:33)
    at _ZoneDelegate.invoke (zone.js:367:52)
    at Zone.run (zone.js:129:43)
    at zone.js:1257:36
    at _ZoneDelegate.invokeTask (zone.js:402:31)
    at core.mjs:27127:55
    at AsyncStackTaggingZoneSpec.onInvokeTask (core.mjs:27127:36)
    at _ZoneDelegate.invokeTask (zone.js:401:60)
    at resolvePromise (zone.js:1193:31)
    at zone.js:1100:17
    at zone.js:1116:33
    at asyncGeneratorStep (asyncToGenerator.js:6:1)
    at _throw (asyncToGenerator.js:25:1)
    at _ZoneDelegate.invoke (zone.js:368:26)
    at Object.onInvoke (core.mjs:27450:33)
    at _ZoneDelegate.invoke (zone.js:367:52)
    at Zone.run (zone.js:129:43)
    at zone.js:1257:36

Is there something I need to do additionally?

[noppa]

What kind of bundler/build setup are you using? The stack trace implies that there may be some stuff going on that isn't coming from this lib, but probably zone.js. Sooo... Angular? What does your ng version (or npx ng version or something) say?

[noppa]

The only way that I can think of that this could happen is that if this line in index.js throws

worker = new Worker(new URL('./xmllint-browser.mjs', import.meta.url), { type: 'module' });

Then worker will be undefined, and I guess I have a bit of an error handling bug in there that we kinda swallow the original error when we fail to terminate the never-created worker in finally.

Until the error handling problem is fixed, I recommend you open the index-browser.mjs file under node_modules, and try removing this line

.finally(() => worker.terminate());

That won't fix the actual issue, but it will fix the poor error message and might give us better hint on why the worker can't be initialized.

[YOUR1]

What kind of bundler/build setup are you using? The stack trace implies that there may be some stuff going on that isn't coming from this lib, but probably zone.js. Sooo... Angular? What does your ng version (or npx ng version or something) say?

Yeah, indeed. I'm using Angular (16.2.1);

[noppa]

I have fixed the confusing Cannot read properties of undefined error on version 4.0.2. This won't fix your actual issue, because for some reason or another the code running in your environment is not able to do new Worker(...). But at least now it's easier to find the original error and focus on solving the actual issue, rather than an unrelated error that is more of an effect rather than the cause.