add error when input channel is not corpus

[f-hafner]

Issue

Workaround to fix #42

Description of changes

• Added an Error property to the actor analysis widget
• raises error when wrong input type for stories. The error only goes away when the right input for Stories is provided.

Questions

• should we also check input types for story_elements? What is the exact control flow then, with the if story_elements is not None
• should we also do the same for the action analysis widget?

Includes

• Code changes

[kodymoodley]

Nice @f-hafner! The message works for the inputs / outputs you give in your example. This case:

...But it doesn't work in this case:

It should throw an error message there too.

There is another minor issue, the error message does not go away once you correct the input:

Otherwise I think your general solution is very nice and practical!

Regarding your questions, indeed also check for story_elements and also apply the same solution to action widget.

[f-hafner]

@kodymoodley , I fixed as you suggested, both for Actors and Actions.

There is a message residual_error in error_handling.py. It was intended to capture other errors when data are processed, but it's dfficult to capture all edge cases, and I'm not sure it's the best way to deal with such errors anyway.
If you disagree, we can discuss how this should be incorporated.
If you want me to remove the message, let me know.
Otheriwse this can be merged from my side.