Be more defensive around SortedList key

Fixes #3885
Part of microsoft/vscode#151225

src/common/SortedList.ts

@@ -34,6 +34,9 @@ export class SortedList<T> {
       return false;
     }
     const key = this._getKey(value);
+    if (key === undefined) {
+      return false;
+    }
     let i = this._search(key, 0, this._array.length - 1);
     if (i === -1) {
       return false;
@@ -75,10 +78,11 @@ export class SortedList<T> {
       return min;
     }
     let mid = Math.floor((min + max) / 2);
-    if (this._getKey(this._array[mid]) > key) {
+    const midKey = this._getKey(this._array[mid]);
+    if (midKey > key) {
       return this._search(key, min, mid - 1);
     }
-    if (this._getKey(this._array[mid]) < key) {
+    if (midKey < key) {
       return this._search(key, mid + 1, max);
     }
     // Value found! Since keys can be duplicates, move the result index back to the lowest index

src/common/services/DecorationService.ts

@@ -19,7 +19,7 @@ export class DecorationService extends Disposable implements IDecorationService
    * while marker line values do change, they should all change by the same amount so this should
    * never become out of order.
    */
-  private readonly _decorations: SortedList<IInternalDecoration> = new SortedList(e => e.marker.line);
+  private readonly _decorations: SortedList<IInternalDecoration> = new SortedList(e => e?.marker.line);
 
   private _onDecorationRegistered = this.register(new EventEmitter<IInternalDecoration>());
   public get onDecorationRegistered(): IEvent<IInternalDecoration> { return this._onDecorationRegistered.event; }
@@ -28,10 +28,6 @@ export class DecorationService extends Disposable implements IDecorationService
 
   public get decorations(): IterableIterator<IInternalDecoration> { return this._decorations.values(); }
 
-  constructor() {
-    super();
-  }
-
   public registerDecoration(options: IDecorationOptions): IDecoration | undefined {
     if (options.marker.isDisposed) {
       return undefined;