message: Changed 'let' to 'const'.
diff: @@ -558,7 +558,7 @@ export class HistoryTracker {
  if (this.currentHistoryStepIndex === 0) {
  return undefined;
  }
  - let lastChangeIndex = this.historySteps[this.currentHistoryStepIndex].changes.length;
  + const lastChangeIndex = this.historySteps[this.currentHistoryStepIndex].changes.length;
  if (lastChangeIndex === 0) {
  return undefined;
  }
  