Raise and handle an exception if qr_code_url is not generated

[mikejgray]

          Nothing is displayed; it probably would be worth raising an exception if we handled those exceptions and present them to the user somehow

Originally posted by @NeonDaniel in #48 (comment)

[NeonDaniel]

Not sure how we want to manage this, but some ideas:

• Speak an error message in the plugin; not sure how actionable it could be but better than quietly failing with a blank screen
• Show an error message and return to the home screen?
• Requires more planning and related work, but we could define some message to emit for exceptions that can't be handled nicely; the support helper skill or some plugin could then decide to send an email or log to some specific path for debugging

[mikejgray]

Do we have any existing examples of plugins speaking? That's usually reserved for skills but easy enough to make happen with a bus message. Curious if we can follow an existing pattern

[NeonDaniel]

Do we have any existing examples of plugins speaking? That's usually reserved for skills but easy enough to make happen with a bus message. Curious if we can follow an existing pattern

Not that I know of; I guess other plugins usually just display a gui page without any audio (i.e. network connection failure)