message: Replace some filter.rs unwrap() to expect()
diff: @@ -159,10 +159,11 @@ fn parse_expr<'a, T: 'static + Debug>(
  ConditionBase::Literal(literal) => Some(Parsed::LiteralRef(literal)),
  ConditionBase::NestedSelect(statement) => {
  let params = fetch_select_params(storage, statement);
  - let first_row = select(storage, statement, &params, Some(filter_context))
  + let value = select(storage, statement, &params, Some(filter_context))
  + .map(Row::take_first_value)
  .next()
  - .unwrap();
  - let value = Row::take_first_value(first_row).unwrap();
  + .expect("Row does not exist")
  + .expect("Failed to take first value");
  Some(Parsed::Value(value))
  }
  