Predefined type 'System.Index' is not defined or imported

'ReadOnlySequence<byte>' does not contain a definition for 'FirstSpan' and no accessible extension method 'FirstSpan' accepting a first argument of type 'ReadOnlySequence<byte>' could be found (are you missing a using directive or an assembly reference?)

'SequenceReader<byte>' does not contain a definition for 'TryReadTo' and no accessible extension method 'TryReadTo' accepting a first argument of type 'SequenceReader<byte>' could be found (are you missing a using directive or an assembly reference?)

Missing compiler required member 'System.Index..ctor'

Predefined type 'System.Index' is not defined or imported

Predefined type 'System.Range' is not defined or imported

Missing compiler required member 'System.Index..ctor'

Predefined type 'System.Index' is not defined or imported

'ReadOnlySequence<byte>' does not contain a definition for 'FirstSpan' and no accessible extension method 'FirstSpan' accepting a first argument of type 'ReadOnlySequence<byte>' could be found (are you missing a using directive or an assembly reference?)

'SequenceReader<byte>' does not contain a definition for 'TryReadTo' and no accessible extension method 'TryReadTo' accepting a first argument of type 'SequenceReader<byte>' could be found (are you missing a using directive or an assembly reference?)

Unreachable code detected

Possible null reference argument for parameter 'json' in 'JsonDocument JsonDocument.Parse(string json, JsonDocumentOptions options = default(JsonDocumentOptions))'.

Possible null reference argument for parameter 'connectionString' in 'MySqlConfiguration MySqlConfiguration.Parse(string connectionString)'.

'MySqlConnection.BeginDbTransactionAsync(IsolationLevel, CancellationToken)': new protected member declared in sealed type

'SqliteConnection.BeginDbTransactionAsync(IsolationLevel, CancellationToken)': new protected member declared in sealed type

Possible null reference argument for parameter 'connectionString' in 'MySqlConfiguration MySqlConfiguration.Parse(string connectionString)'.

Nullability of type of parameter 'value' doesn't match overridden member (possibly because of nullability attributes).

Nullability of type of parameter 'value' doesn't match overridden member (possibly because of nullability attributes).

Possible null reference argument for parameter 'connectionString' in 'PostgresConfiguration PostgresConfiguration.Parse(string connectionString)'.