In table filter criterion editor, specifying empty strings (as well as NULLs) for the "between" values causes an error

[leehart]

Home > Data > P.f.6.0 Release > Samples
Click "Add filter"
Click "Add criterion"
Select "Latitude" column
Select "Between" comparison
See that no values have been specified by default.
Click "Apply"
See error.

Note that if you (go back to the criterion editor and) click in the empty boxes and outside them (focus then blur), the empty strings are automatically converted to NULL values, which also causes an error.

(Maybe related to #463, i.e. monetdb type conversion.)
Except this is conversion of a particular string to a float:

OperationalError: 22018!conversion of string 'None' to type flt failed.

Instead of conversion of string to integer.