Why do empty strings with integers get converted to zero?

[flexatone]

>>> ak.iterable_str_to_array_1d(['', '3'])
array([0, 3])

>>> ak.iterable_str_to_array_1d(['', '3'], dtype=int)
array([0, 3])

[flexatone]

This happens for two reasons:

1. AK_UCS4_to_int64, if given all empty field, returns an npy_int64 of 0; this cannot easily return an error code. Also: AK_UCS4_to_uint64 does the same thing.
2. AK_CPL_current_to_bool, similarly, treats empty or non "true" values as 0.
3. When auto-type detection is used, it is the logic in AK_TPS_Resolve that, if previous is TPS_INT and new is TPS_EMPTY, we return TPS_INT; this is the same for TPS_FLOAT and TPS_BOOL.

[flexatone]

This is the same for Boolean arrays, where the default is False:

>>> ak.iterable_str_to_array_1d(('', 'true'))
array([False,  True])