This makes sure the error message visible in the error stack created
when using `assert.fail()` without any arguments or the message set
to `undefined` or `null` as only argument.
That was masked before due to other changes.

This makes sure that the error message is more appropriate than
before by checking closer what operator is used and which is not.

It also increases the total number of lines printed to the user.

This reduces the total amount of reads when using `assert.ok()` with
a falsy value. That increases the read performance significantly.

Also remove a comment that can not be addressed.