AT:

• the license check does not throw an error in the logs, but shows a hint that the license needs to be added
• the actually stack trace is only thrown if the log level is debug
• the new output looks similar to this:

  ############### Heads up ################
  You tried to access Optimize, but no valid license could be
  found. Please enter a valid license key!  If you already have 
  a valid key you can have a look here, how to add it to Optimize:
  
  https://docs.camunda.org/optimize/2.3/user-guide/license/ 
  
  In case you don't have a valid license, feel free to contact us at:
  
  https://camunda.com/contact/
  
  You will now be redirected to the license page...
  

  -> The Optimize Docs version should be automatically adjusted to the used version.