anchor.diff:  
         return size;
       } else if (ref.isFiltered) {
  -      final snapshot = ref.controller.getSnapshot(ref);
  -      final sum = sizeAllVisibleLibraries(snapshot?.libraryRoot?.children);
  +      final snapshot = ref.controller!.getSnapshot(ref)!;
  +      final sum = sizeAllVisibleLibraries(snapshot.libraryRoot?.children ?? []);
         final snapshotGraph = snapshot.snapshotGraph;
         return snapshotGraph.shallowSize - sum;
       } else if (ref.isExternals) {
  -      final snapshot = ref.controller.getSnapshot(ref);
  +      final snapshot = ref.controller!.getSnapshot(ref)!;
         return snapshot.snapshotGraph.externalSize;
       } else if (ref.isExternal) {
         return (ref as ExternalReference).sumExternalSizes;
  
positive.code:   _LibraryRefColumn() : super('Library or Class');
  
    @override
    dynamic getValue(Reference dataObject) {
      // Should never be empty when we're displaying in table.
      assert(!dataObject.isEmptyReference);
  
      String value;
      if (dataObject.isLibrary) {
        value = (dataObject as LibraryReference).name;
        final splitValues = value.split('/');
  
        value = splitValues.length > 1
            ? '${splitValues[0]}/${splitValues[1]}'
            : splitValues[0];
      } else {
        value = dataObject.name;
      }
      return value;
    }
  
    @override
  
negative.code:       );
      }
  
      final rightSideTable = _controller.isLeafSelected
          ? InstanceTreeView()
          : _controller.isAnalysisLeafSelected
              ? Expanded(child: AnalysisInstanceViewTable())
              : helpScreen();
  
  