Own Theme only works in dark mode .JSON

Product: PowerShell Universal
Version: 5.6.12

Happy New Year, everyone. I am currently working on creating a custom theme for our PSU apps. For this, I wanted to use a copy of ‘Afterglow.JSON’ theme as a basis and only change the colors slightly. If I save it under the theme folder, I can access it as long as the last theme was run in dark mode. However, when I switch to light mode, I get an error message from React: Objects are not valid as a React child (found: [object Error]). If you meant to render a collection of children, use an array instead.