can't get ignore messages to work

While linting, I want to get rid of `E501 line too long (x > 79 characters)` so I tried added the following to my config, but nothing worked, even after restarting micro:

```json
    "lsp.ignoreMessages": "E501 line too long",
```
```json
    "lsp.ignoreMessages": "E501",
```

I'm using the latest version 0.6.3 and also checked that it wasn't working with 0.6.2.