FIX corner-case of bean browser failing due to an exception from hashCode()

I know this is a corner-case, but when a bean exposes an object as a property whose `hashCode()` method can fail, it kills entire bean browser. For example, with an ArrayList being changed at high frequency, its `hashCode()` can throw `ConcurrentModificationExcpetion`.

Doing object-identity based test for  `alreadyWritten` will fix it, but I don't know the good way to implement it (there's `System.identityHashCode(Object)`, but there's no real guarantee for uniqueness). For now, this patch simply catches exceptions from `hashCode()` and assumes it's never seen before.