Problem Description:

The browser reported an error of ‘stylesheets undefined’

this.sheetData.styleSheets = "";

Cause analysis:

In some scenarios, stylesheets do not exist, causing the browser to report an error and are not defined

Solution:

Add a judgment. If stylesheets does not exist, this attribute will be automatically added and null value will be assigned.

if (this.sheetData) {
      this.sheetData['styleSheets'] = "";
    }