Dereference of a possibly null reference.

Nullability of reference types in value of type 'Converter<T?>' doesn't match target type 'Converter<T, string>'.

Dereference of a possibly null reference.

Possible null reference argument for parameter 'collection' in 'HashSet<T?>.HashSet(IEnumerable<T?> collection, IEqualityComparer<T?>? comparer)'.

Dereference of a possibly null reference.

Dereference of a possibly null reference.

Nullability of reference types in type of parameter 'sender' of 'void MudWatch.Elapse(object sender, ElapsedEventArgs args)' doesn't match the target delegate 'ElapsedEventHandler' (possibly because of nullability attributes).

Dereference of a possibly null reference.

The type 'T' cannot be used as type parameter 'TKey' in the generic type or method 'Dictionary<TKey, TValue>'. Nullability of type argument 'T' doesn't match 'notnull' constraint.