Unable to get Planka Helm Chart to accept a base URL


I’m unable to get the Planka Helm Chart to accept any reasonable value for the required base URL parameter. ex: http://localhost:31000 (from the CI pipeline settings). The error is:

Invalid format or character.

It has been a few years since I’ve authored any Helm Charts and so I don’t really recall how one sets the schema for variables.

Anyone seen similar? Have any tips?