“Internal Server Error” after successful deployment with render

I wanted to do my first nodejs deployment with render.com. The deployment of my web service is successfully completed.
However, after completing the deployment (https://one4-01-1.onrender.com/) with render, I receive an “Internal Server Error”. I have already created an .env file in my GitHub, and also created a secret file in render.
The console gives me the following: Uncaught TypeError: Cannot read properties of undefined (reading ‘parentNode’) , and: GET https://one4-01-1.onrender.com/ 500
What options do I have to find out where my error is and how I can fix it? Has anyone ever had the same problem after deployment?

I have already created an .env file in my GitHub, and also created a secret file in render. I also tried to integrate the secrets into the javascript file so that I did not need an .env file. Also I tried to add an web.config file (Since I have seen this in the answers to other questions):

<configuration>
  <system.webServer>
    <validation validateIntegratedModeConfiguration="false" />
  </system.webServer>
</configuration>