https://github.com/mozilla/pdf.js/blob/0df1a5661958df0c4ed2f73b0f3266d825c5c280/src/display/api.js#L710-L719
The return type signature `@returns {Promise<{num: number, gen: number}>}` is mismatched with its definition. (should be `@returns {Promise<number>}`)
if (!intentState) {
      intentState = Object.create(null);
      this._intentStates.set(renderingIntent, intentState);
    }
    let opListTask;
    if (!intentState.opListReadCapability) {
      opListTask = Object.create(null);
      opListTask.operatorListChanged = operatorListChanged;
      intentState.opListReadCapability = createPromiseCapability();
      (intentState.renderTasks ||= new Set()).add(opListTask);
      intentState.operatorList = {
        fnArray: [],
        argsArray: [],
        lastChunk: false,
      };
      if (this._stats) {
        this._stats.time("Page Request");
      }
      this._pumpOperatorList({
        pageIndex: this._pageIndex,
        intent: renderingIntent,
      });
    }
    return intentState.opListReadCapability.promise;
  }
  /**
   * @param {getTextContentParameters} params - getTextContent parameters.
   * @returns {ReadableStream} Stream for reading text content chunks.
   */
  streamTextContent({