Small bugs with Gen.hs

[jiegillet]

Some bugs I found when running tests:

• The string "\" can be generated as a key, but is invalid because the escape character cannot be on its own
• It can generate an array a which contains two arrays b and b.c on the same level, which pretty prints to [[a]] \n [[a.b]] \n [[a.b.c]] but that gets (correctly) interpreted as an array a that contains an array b that contains an array c. Elements of an array can't share prefixes.

The first one should be easy to fix, the second is trickier maybe, but overall those have very small chance of appearing, and if they do, re-running the test has always done the trick for me. Maybe not worth fixing.

[chshersh]

@jiegillet Let's fix the first problem because it's the easiest one. And keep the issue open. Maybe somebody would like to practice in implementing generators 🙂

[chshersh]

The first part was fixed. The second part will require more effort to fix and it doesn't cause any troubles so far, so I'm closing the issue.