Methods which never return (like run) should be marked as `-> Never`

[helje5]

As per PR #150, which needs to be fixed in more places.

Note that this is API semver major, so for 2.x.

[helje5]

Of course you should be very sure whether you want the Never behaviour, but if you do - as documented -, it should return Never.

Why might you not want Never? I don't know, maybe because some Lambda's would want to switch the bootstrap for some crazy reason?

[tomerd]

lets do this with other breaking API changes for 1.0