Better error message if passed in a column name instead of a list of column names into `custom_data`

[chriddyp]

custom_data is unlike most other px properties in that it accepts a list of columns instead of just a single column.

It would be helpful if we said something like "Looks like you supplied a single column name, you should supply a list of columns."

Here's the current error:

ValueError: Value of 'custom_data_0' is not the name of a column in 'data_frame'. Expected one of ['uid', 'from_uid', 'dropout', 'embedding_size', 'epoch', 'lr', 'train f1', 'valid ppl'] but received: 19751736_1

[emmanuelle]

Good idea. Same for hover_data and maybe a couple of others. We'll have to find a clever workaround though to see at which level to catch the error.

[chriddyp]

It would also be helpful if we noted which attribute had an error. So, for the error message above, saying something like:

You supplied a single column name to the property custom_data. This property only accepts a list of column names. Try supplying custom_data=["your-column"] instead of custom_data="your-column"

[PandaTinker]

If we let the parser automatically convert "your-column" to ["your-column"], will there be any consequence?

[nicolaskruchten]

I'd rather we provide a helpful error message for all the array_attrables if what's provided for them is not list-like :)