.json files not included in database

When creating a database with javascript as the language, I expect .json files to be included. But, they are not.

**Steps to reproduce**:

1. Create a folder `t`
2. Create the following files in it
1. **dummy.js** (This is only here to disable the warning that there is no code)
```
(function(){window.console.log("")})();
```
2. **file.json**
```
{
"M": "6"
}
```
3. Create the database
`codeql database create -s t -l javascript output`

The created database contains `dummy.js`, but not `file.json`.

I tested this with both CLI 2.10.0 and 2.10.1.

**Question**: Is this a bug? Or am I wrong when I assumed this is supposed to work? Are there any simple workarounds?

If you are wondering why I want this to work, the reason is that I want to write my own CodeQL queries to check some json configuration files.