Make widget tests throw when a modal is shown

[AndrewFerr]

Instead of waiting for tests to time out if they show a dialog that they cannot interact with, throw an error immediately if a dialog is shown.

Signed-off-by: Andrew Ferrazzutti andrewf@element.io

Checklist

• Tests written for new code (and old code if feasible).
• New or updated public/exported symbols have accurate TSDoc documentation.
• Linter and other CI checks pass.
• Sign-off given on the changes (see CONTRIBUTING.md).

[t3chguy]

This change does not match its title. The test is not responsible for making the app fail fast

[t3chguy]

@AndrewFerr do you need me to hit the merge button or are you able to yourself?

[AndrewFerr]

@AndrewFerr do you need me to hit the merge button or are you able to yourself?

The former, as I currently don't have write access to this repo.