bf luis:convert failed to convert the lu

[xhr0804]

Versions

@microsoft/botframework-cli/4.9.0-preview.113642 win32-x64 node-v12.14.1

Describe the bug

When we convert a .json file to .lu or export a .lu file directly from luis portal. The .lu file will include the "usesFeatures" line for each intent no matter it contains a feature or not. But when we convert it back to .json, we will get an error for the line.

## None
- all of them
- i want them all
- i want to all of them

@ intent None

To Reproduce

Copy the lines above and use bf luis:convert to convert it to .json.