diff --git a/packages/nbdime/src/diff/widget/linked-cells.ts b/packages/nbdime/src/diff/widget/linked-cells.ts
index 56cc0f83..ed3e4513 100644
--- a/packages/nbdime/src/diff/widget/linked-cells.ts
+++ b/packages/nbdime/src/diff/widget/linked-cells.ts
@@ -200,12 +200,16 @@ class LazyDisplayLinkedListCell extends LinkedListCell {
 
   showLazyCellUp() {
     this.showLazyCell();
-    this._prev?.expandUp();
+    if (this._prev) {
+      this._prev.expandUp();
+    }
   }
 
   showLazyCellDown() {
     this.showLazyCell();
-    this._next?.expandDown();
+    if (this._next) {
+      this._next.expandDown();
+    }
   }
 
   showLazyCell() {
diff --git a/packages/nbdime/src/diff/widget/notebook.ts b/packages/nbdime/src/diff/widget/notebook.ts
index 2be870ff..9ba18899 100644
--- a/packages/nbdime/src/diff/widget/notebook.ts
+++ b/packages/nbdime/src/diff/widget/notebook.ts
@@ -8,7 +8,7 @@ import type {
   IRenderMimeRegistry
 } from '@jupyterlab/rendermime';
 
-import { ILinkedListCell, LazyDisplayLinkedListCell, LinkedListCell } from "./linked-cells";
+import { LazyDisplayLinkedListCell, LinkedListCell } from "./linked-cells";
 import { CellDiffWidget } from "./cell";
 import {
   CHUNK_PANEL_CLASS,
@@ -18,30 +18,28 @@ import {
 
 import { MetadataDiffWidget } from "./metadata";
 
-import { NotebookDiffModel, CellDiffModel } from "../model";
+import type { NotebookDiffModel, CellDiffModel } from "../model";
 
 const NBDIFF_CLASS = "jp-Notebook-diff";
 
-type Command<T> = new (renderFunc: ()=> CellDiffWidget) => T
-
 
 /**
  * NotebookDiffWidget
  */
 export class NotebookDiffWidget extends Panel {
+  private _model: NotebookDiffModel;
+  private _rendermime: IRenderMimeRegistry;
+  private previousCell: LinkedListCell | null;
+
   constructor(
     model: NotebookDiffModel,
     rendermime: IRenderMimeRegistry,
-    displayedCellWrapper: Command<ILinkedListCell> = LinkedListCell,
-    lazyDisplayWrapper: Command<LazyDisplayLinkedListCell> = LazyDisplayLinkedListCell
   ) {
     super();
     this._model = model;
     this._rendermime = rendermime;
     this.addClass(NBDIFF_CLASS);
     this.previousCell = null;
-    this.displayedCellWrapper = displayedCellWrapper;
-    this.lazyDisplayWrapper = lazyDisplayWrapper;
   }
 
   /**
@@ -145,10 +143,4 @@ export class NotebookDiffWidget extends Panel {
   get model(): NotebookDiffModel {
     return this._model;
   }
-
-  private _model: NotebookDiffModel;
-  private _rendermime: IRenderMimeRegistry;
-  private previousCell: LinkedListCell | null;
-  private displayedCellWrapper: Command<ILinkedListCell>;
-  private lazyDisplayWrapper: Command<ILinkedListCell>;
 }
diff --git a/packages/nbdime/src/styles/variables.css b/packages/nbdime/src/styles/variables.css
index 49935ff3..258f9610 100644
--- a/packages/nbdime/src/styles/variables.css
+++ b/packages/nbdime/src/styles/variables.css
@@ -29,7 +29,7 @@
   --jp-merge-either-color2: #cff4f4;
   --jp-expand-outer-wrapper: rgb(221, 244, 255);
   --jp-expand-color: rgb(87, 96, 106);
-  --jp-expand-a-color: rgba(84, 174, 255, 0.4)
+  --jp-expand-a-color: rgba(84, 174, 255, 0.4);
   --jp-expand-svg-color: rgb(87, 96, 106);
   --jp-expand-a-hover-color: rgb(14, 94, 208);
   --jp-expand-a-hover-svg-color: rgb(255, 255, 255);
diff --git a/packages/webapp/src/app/diff.ts b/packages/webapp/src/app/diff.ts
index 30349307..08f2d2c9 100644
--- a/packages/webapp/src/app/diff.ts
+++ b/packages/webapp/src/app/diff.ts
@@ -2,8 +2,6 @@
 // Distributed under the terms of the Modified BSD License.
 "use strict";
 
-import * as nbformat from "@jupyterlab/nbformat";
-
 import type * as nbformat from '@jupyterlab/nbformat';
 import { Panel, Widget } from "@lumino/widgets";
 
@@ -11,8 +9,6 @@ import { RenderMimeRegistry } from "@jupyterlab/rendermime";
 
 import { defaultSanitizer } from "@jupyterlab/apputils";
 
-import { PageConfig } from "@jupyterlab/coreutils";
-
 import type {
   IDiffEntry
 } from 'nbdime/lib/diff/diffentries';
@@ -27,6 +23,7 @@ import { getBaseUrl, getConfigOption, toggleSpinner } from "./common";
 import { exportDiff } from "./staticdiff";
 
 import { rendererFactories } from "./rendermime";
+import { MathJaxTypesetter } from "@jupyterlab/mathjax2";
 
 let diffWidget: NotebookDiffWidget | null = null;