Cannot convert null literal to non-nullable reference type.

Non-nullable field '_chkS1ExclLonger' must contain a non-null value when exiting constructor. Consider adding the 'required' modifier or declaring the field as nullable.

Non-nullable field '_chkS1ExclShorter' must contain a non-null value when exiting constructor. Consider adding the 'required' modifier or declaring the field as nullable.

Non-nullable field '_chkS1ExclFewer' must contain a non-null value when exiting constructor. Consider adding the 'required' modifier or declaring the field as nullable.

Non-nullable field '_chkS1DupLines' must contain a non-null value when exiting constructor. Consider adding the 'required' modifier or declaring the field as nullable.

Non-nullable field '_chkS1NoCounter' must contain a non-null value when exiting constructor. Consider adding the 'required' modifier or declaring the field as nullable.

Non-nullable field '_chkS1Styled' must contain a non-null value when exiting constructor. Consider adding the 'required' modifier or declaring the field as nullable.

Non-nullable field '_txtS1Exclude' must contain a non-null value when exiting constructor. Consider adding the 'required' modifier or declaring the field as nullable.

Non-nullable field '_txtS1Include' must contain a non-null value when exiting constructor. Consider adding the 'required' modifier or declaring the field as nullable.

Nullability of reference types in type of parameter 'other' of 'int InfoLine.CompareTo(InfoLine other)' doesn't match implicitly implemented member 'int IComparable<InfoLine>.CompareTo(InfoLine? other)' (possibly because of nullability attributes).