Map type is mistaken for array type

[chrisrichardson77]

The library segfaults when running the example code. The segfault is due to a recursion in the exception handling code where an attempt is made to construct and exception object which in turn throws an exception.

This last exception is thrown because ucontainer incorrectly converts a map key to an integer zero, assumes that this means the type is an array, then consistently returns the zeroth element instead of a value based on what should have been a map key.