Add a new throwPlayFunctionExceptions parameter

[tmeasday]

Issue: Play function errors were swallowed if you didn't have the interactions addon installed.

What I did

• Add parameters.hidePlayFunctionExceptions
• If unset, revert to throwing play function errors
• Set it in the interactions addon

How to test

• See unit tests
• Run a sandbox, throw an error in a play function. Check it is still swallowed.
• Disable the interactions addon, check the play function is displayed:

How to set in external tools (e.g. Chromatic)

1. Browse to iframe.html.
2. Update project parameters:

const preview = __STORYBOOK_PREVIEW__
const { projectAnnotations } = preview.storyStore;
const newAnnotations = {
  ...projectAnnotations,
  parameters: {
    ...projectAnnotations.parameters, 
    throwPlayFunctionExceptions: false,
  },
};

preview.onGetProjectAnnotationsChanged({ getProjectAnnotations: () => newAnnotations })

3. Render story as usual.

[tmeasday]

@ghengeveld one thing: in this implementation, the sequence of events is changed if parameters.hidePlayFunctionExceptions is set:

1. With it set, we only throw PLAY_FUNCTION_THREW_EXCEPTION, the story ends up in phase "completed"
2. With it unset, we throw PLAY_FUNCTION_THREW_EXCEPTION, then STORY_THREW_EXCEPTION and the story ends up in phase "errored".

I'm thinking in case 2, instead we probably want to show the error in the UI, but still end up completing the story without throwing a STORY_THREW_EXCEPTION. WDYT?

[yannbf]

Question: why is the config set as a parameter (which could be changed at a story level for instance) and not as a core or features property from main.js/presets?

[tmeasday]

Question: why is the config set as a parameter (which could be changed at a story level for instance) and not as a core or features property from main.js/presets?

Good question! I don't think it's a feature, but a core property might make sense. I guess the main reason to use a parameter is to allow Chromatic to change it easily, I'm not sure how you'd change a core property from outside the SB build (maybe you can just update window.X directly?)

[tmeasday]

Discussed with @shilman. In the future we might want to consider a proper "options store" in the preview, and also mechanisms/APIs for changing options at runtime. For now, it isn't really safe to change options at runtime, so we have to use parameter for this. We already have some other parameters that are really options so I guess we aren't exactly making things "worse" 🤷

[ghengeveld]

Overall LGTM. I'd like to see it renamed to throwPlayFunctionExceptions though.