Flag to shorten error output about provider

[rrousselGit]

I'm not fond of the idea.
I don't want to have random configuration flags for such a thing.

But we can improve the message if you have any idea on what could be made better

[Lootwig]

How about an FAQ (or "Frequently Done Wrong") one-liner URL instead? For reference, the current instructions are 45 lines long

[Lootwig]

Alternatively, swap the order of the instructions and the info which provider was missing, so that an auto-scrolling console will have the most relevant info at the bottom:

- [provider how-to...]
- Error: Could not find the correct Provider<$valueType> above this $widgetType Widget
- [Stacktrace]

[rrousselGit]

Maybe we could show the type both at the start and the end.
Having it at the start is important I think.

In any case, I don't care too much about this. Fancy making a PR?