fix __repr__ of dataset

[peendebak]

The .name and .array_id fields of a DataArray can be None. This fixes an error generated when a DataSet contains such a DataArray.

@alexcjohnson @giulioungaretti Is it an idea to gather multiple of these small fixed into a single branch like onelinefixes. This would decrease the number of PRs.

[MerlinSmiles]

Thanks, good catch :)
I'd prefer to have '' instead of 'None' that makes it a bit clearer to me that it is missing.

Where did you run into this?

It just happened to me when I was running the load-old-data notebook while working on the array_id's Basically when a snapshot is missing it wont have that information.

[alexcjohnson]

Is it an idea to gather multiple of these small fixed into a single branch like onelinefixes. This would decrease the number of PRs.

I'd say we've actually been erring on the other side, PRs that are too big - I'm no exception to that - but ideally a PR has a single topic - fixing a single bug, adding a single feature. If that only takes one line, all the better, it'll be super easy to review and approve.

And to that point, good catch, 💃 !
@MerlinSmiles thanks for the linting.

[MerlinSmiles]

@alexcjohnson do you have a preference for none vs empty string as a replacement?

[alexcjohnson]

do you have a preference for none vs empty string as a replacement?

Not really. array_id should probably never be None as long as the array is part of a DataSet (which it clearly is since this is the DataSet repr!) - because it should match the array's key in DataSet.arrays. name I'm not sure we'll even have a use for once we sort out better array_id conventions (ala #197 ) so I see this as a short-term fix anyway.

[MerlinSmiles]

not sure about the ids but names can be empty I think. And also I dont think name should be the same as the ID, is that what you mean.

[peendebak]

@MerlinSmiles I found the issue when writing a dataset to disk and then loading it again.
@alexcjohnson I agree that array_ids should not be None. Best thing would be to remove the default initializer in the DataSet constructor, but I'll leave that for another PR.