Cloudfront Function FunctionConfig is required to deploy

[woodworker]

The documentation states that FunctionConfig is optional/not required but when i want to deploy a function i get a very unhelpful error and a failed deployment

Resource handler returned message: "null" (RequestToken: xxx-xxx-xxx-xxx-xxx, HandlerErrorCode: InternalFailure)

In https://github.com/awsdocs/aws-cloudformation-user-guide/blob/main/doc_source/aws-resource-cloudfront-function.md it is stated that FunctionConfig is not required is. As there is also the FunctionCode as not required marked is this an dependency? As in if there is FunctionCode given you also MUST give a FunctionConfig? If yes, this should also be noted in the documentation.