index: try/catch the Object.getOwnPropertyNames() call

There is a possibility that this function may throw when given a native
host object
index: try/catch the Object.getOwnPropertyDescriptor() call

On IE10 and probably others, this was a source of the `inspect()` call failing
Merge pull request #1 from TooTallNate/add/try-catches

Add `try/catch` clauses around a couple Object.*() functions