Suppress exception when mapping field of unknown type
By default, the
FilterDataSet class will iterate over all fields and
CastAndCall on each one to call the subclass' mapping function
with the appropriate array type.
This only works if the array is of a known type. If it is not
CastAndCall throws an exception. However, having the entire filter
exception out just because one field cannot be converted does not make
sense. Instead, catch the exception, log a warning, and drop the field.