fix: resolve 14 code-review issues across Core/Differential/Bowl/Drivelution/Extension - #513

Converting null literal or possible null value to non-nullable type.

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

Non-nullable field 'll8' must contain a non-null value when exiting constructor. Consider adding the 'required' modifier or declaring the field as nullable.

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

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

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

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

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

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

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

NOTICE: windows-latest requests are being redirected to windows-2025-vs2026 by June 15, 2026