Dont show diff if no base-lcov-file

[TanguyRMalou]

In the readme, there this description for the base-lcov-file argument :
Lcov.info file that would be used to compare code coverage. The comparison will be disabled if the file is not passed

But if I don't pass and lcov file, I have the line : Your code coverage diff: NaN% ▴ but it shouldn't be here according to the description

[vitaliimelnychuk]

Hello @TanguyRMalou!

Thanks for reporting it, you're right - it shouldn't be there in the first place. Feel free to create a PR once you have a chance.

Meantime, can you post your configuration of action here as well?