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

Process completed with exit code 1.

Nullability of reference types in value of type 'var' doesn't match target type 'INamedTypeSymbol'.