anchor.diff:      // use it everywhere it appears.
       return _typeTable.nameType(type, typeRep);
     }
  +
  +  void /* Never */ _undeterminedNullabilityError(DartType type) =>
  +      throw UnsupportedError(
  +          'Undetermined Nullability encounted while compiling '
  +          '${currentLibrary.fileUri}, which contains the type: $type.');
   
     /// Wraps [typeRep] in the appropriate wrapper for the given [nullability].
     ///
  
positive.code:     }
  
      if (type.nullability == Nullability.undetermined) {
        throw UnsupportedError('Undetermined Nullability');
      }
  
      // Emit non-nullable version directly.
  
negative.code:     typeRep ??= _emitFutureOrNameNoInterop();
  
      if (type.declaredNullability == Nullability.undetermined) {
        _undeterminedNullabilityError(type);
      }
  
      // Emit non-nullable version directly.
  