fix: handle undefined or empty image source values

[ThimoDEV]

References #1299

I have been thinking about the best solution for this issue. Typescript says by design that the src prop is string | undefined so we either need to narrow that down or allow it?

Vue by design always adds undefined type as far as I could see. When I removed the throw error it works more as expected and with the reuired property on the src prop I get a Vue warning that it is not set which is nice.

However when I set:

:src="undefined" I get a Vue warning the the type for the src prop is incorrect.

Is it better to match the typescript types (and it quite follows the normal behaviour or have it generate a Vue prop required warning with the above downside?

[toyi]

Allowing undefined would also allow the developer to eventually catch this undefined src in a custom provider and do something else with it (showing a specific placeholder or something else).

Currently, we must pass a string (and '' doesn't work, it throws an error saying it received '' instead of a string). So when the image can be undefined, it must be handled directly where you use the component (or in a high order component).