Can't reference the other JSON schema

I [have](https://github.com/EmilySeville7cfg-Test/ajv-reference-not-found-issue) two `.json` schemas:

- `base.json` (which is referenced in `sample.json`)
- `sample.json`

The problem is I obtain an [error](https://github.com/EmilySeville7cfg-Test/ajv-reference-not-found-issue/runs/4912282024?check_suite_focus=true#step:3:13) when I try check `sample.yml` correctness:

```
schema sample.json is invalid
error: can't resolve reference file:base.json#/$defs/prop from id #
```

What am I missing?