Fix using samplesheetToList multiple times in channel operators

[nvnieuwk]

Fixes #55

[awgymer]

Which part of this was actually the bug?

[awgymer]

All makes sense but would be good to understand why the values were being cached so we don't run into similar issues elsewhere in future?

[nvnieuwk]

I think it's caused by the parallelization of the channel operators. Even though the SamplesheetConverter gets created for every invokation of samplesheetToList it somehow seems to be able to interact with all instances of it. So I think it's just best to only have values that will be the same for all uses of the function (like the config in this case) and simply pass the values that can be changed as inputs to the functions. But maybe @bentsherman can help us out here?

[bentsherman]

It could be parallel if you call samplesheetToList in a process, or across multiple different operators. In that case you should see if your SamplesheetConverter class is using shared variables (i.e. static variables) because that could cause a race condition

[nvnieuwk]

Yes that was the problem indeed, it got fixed by removing those and passing them as inputs to the desired functions instead