Do not use KeyError, TypeError and IndexError

The built-in exception KeyError often occurs in case of bugs in the interpreter. Therefore, it may not be used to raise domain-specific exceptions. Specifically, in get_property_type() it should be replaced by a specific exception, e.g. InvalidKey and handled in errors.py. Unexpected KeyError should remain non-handled.

The same holds for 'TypeError' and 'IndexError'. Bugs in the interpreter cause such exceptions and they are caught by the handler. This should not happen!

Other built-in exceptions being caught by the handler are ValueError and ArithmeticError but these are not very frequently raised due to interpreter bugs. Nevertheless, they should not be used for domain-specific purposes.