Firebase Database (${JSCORE_VERSION}) INTERNAL ASSERT FAILED: Unknown node type

### Version info

**Angular: 14**

**Firebase: 9.9.1**

**AngularFire: 7.4.1**

**Other (e.g. Ionic/Cordova, Node, browser, operating system):**

Node 16.13.0
macOS

### How to reproduce these conditions
#### Steps to set up and reproduce

When a local or production build is served, we have the below console error:
```
zone.js:1061 Unhandled Promise rejection: Firebase Database (${JSCORE_VERSION}) INTERNAL ASSERT FAILED: Unknown node type ; Zone: ; Task: setTimeout ; Value: Error: Firebase Database (${JSCORE_VERSION}) INTERNAL ASSERT FAILED: Unknown node type
```

Also, not sure if because above max call stack also showed:

```
polyfills.js:29650 Uncaught RangeError: Maximum call stack size exceeded
at ChildrenNode.isLeafNode (vendor.js:286427:13)
at ChildrenNode.equals (vendor.js:64135:22)
at ChildrenNode.equals (vendor.js:64140:31)
at ChildrenNode.equals (vendor.js:64140:31)
at ChildrenNode.equals (vendor.js:64140:31)
at ChildrenNode.equals (vendor.js:64140:31)
at ChildrenNode.equals (vendor.js:64140:31)
at ChildrenNode.equals (vendor.js:64140:31)
at ChildrenNode.equals (vendor.js:64140:31)
at ChildrenNode.equals (vendor.js:64140:31)
```

#### Source code from tracing:
```
/**
* Returns an Error object suitable for throwing.
*/
const assertionError = function (message) {
return new Error('Firebase Database (' +
CONSTANTS.SDK_VERSION +
') INTERNAL ASSERT FAILED: ' +
message);
};
```

### Expected behavior
Build runs on both local and production without errors

### Actual behavior
Build runs on both local and production has errors

まず、Angular 14、Firebase 9.9.1、AngularFire 7.4.1、Node 16.13.0 を使ってローカルビルドと本番ビルドを再現します。Firebase Database の assertionError の発生源と、レポートに示されている ChildrenNode.equals のスタックを追跡します。両方のビルドが unknown node type エラーや maximum call stack 例外なしで実行されれば完了です。

索引モデルが issue の本文から書いたものです。