`khal new -i` is too unforgiving when mistakes are made

To Reproduce

khal new -i
calendar: personal    
summary: an event created via khal new -i
datetime range: 3d
critical: Could not parse "3d".
critical: Please check your configuration or run `khal printformats` to see if this does match your configured [long](date|time|datetime)format.
critical: If you suspect a bug, please file an issue at https://github.com/pimutils/khal/issues/ 

Actual behavior
If any mistake, the creation process must start from scratch, providing again every valid field.

Expected behavior
khal should just prompt over and over until it gets SIGINT, or maybe escape, or enter on empty input.

If applicable: Stack Trace
n / a

OS, version, khal version and how you installed it:

• The output of khal --version: khal, version 0.11.3
• Installation method: Alpine distro package
• python version Python 3.11.8
• OS [e.g. arch] Alpine Linux

Start by running khal new -i and trace the interactive creation entry point that handles the datetime range prompt. Reproduce the 3d parsing failure and determine how invalid input currently exits; done means the prompt can retry after a mistake and still permits the documented termination behavior.