Bugzilla

I was using the client to connect to bidi at https://juliandescottes.github.io/bidi-web-client/web/ , and I usually just send an empty session.new command to create the session, but this now fails with a cryptic error message: 

> Expected [object Undefined] undefined to be an object

We should add a custom message on the following assert so that users know that the issue is a missing `capabilities` parameter perhaps?

Sasha: just a quick ping for you to check if this bug is valid?

I was using the client to connect to bidi at https://juliandescottes.github.io/bidi-web-client/web/ , and I usually just send an empty session.new command to create the session, but this now fails with a cryptic error message: 

> Expected [object Undefined] undefined to be an object

We should add a custom message on the [following assert](https://searchfox.org/mozilla-central/rev/962a843f6d96283c45162c788dc72bf217fca7df/remote/shared/webdriver/Capabilities.sys.mjs#976) so that users know that the issue is a missing `capabilities` parameter perhaps?

Sasha: just a quick ping for you to check if this bug is valid?

I was using the client to connect to bidi at https://juliandescottes.github.io/bidi-web-client/web/ , and I usually just send an empty session.new command to create the session, but this now fails with a cryptic error message: 

> Expected [object Undefined] undefined to be an object

We should add a custom message on the [following assert](https://searchfox.org/mozilla-central/rev/962a843f6d96283c45162c788dc72bf217fca7df/remote/shared/webdriver/Capabilities.sys.mjs#976) so that users know that the issue is a missing `capabilities` parameter perhaps?
```javascript
export function processCapabilities(params) {
  const { capabilities } = params;
  lazy.assert.object(capabilities);
```

Sasha: just a quick ping for you to check if this bug is valid?