Give user some form of feedback when the picker enters the "failed" state

[LarsLuz]

Hello,

currently the file-picker app can enter a "failed" state without any kind of feedback. I've encountered this behaviour when a previously accepted Bearer token is no longer valid: the bar on top still loads normally but no files etc. are displayed.

I think that the variable that is set on the following line:

file-picker/src/components/FilePicker.vue

Line 104 in ab37342

this.state = 'failed'

should be checked in the template.

Thanks!