group.by set to NULL in combineExpression fails

[michael-kotliar]

When setting group.by to NULL this line fails because comparing NULL and string doesn't produce any value. is.null(group.by) should go before group.by == "none"

https://github.com/ncborcherding/scRepertoire/blob/d188e6ffe71db03c7f79f86652c9b2378aeceffe/R/combineExpression.R#L79

> NULL == "none"
logical(0)

[ncborcherding]

Hey Michael,

Thanks for pointing this out - you are correct. If you find anymore of these, feel free to make a pull request and get your username on the repo. I think it's important to keep track of that.

Also if you have larger suggestions or functions you might have, feel free to reach out via email. We are in the process of testing out v2 beta and will be writing a manuscript next year, would be happy to have any contribution.

Nick