#157 0.2.8 invoice input: Wanted Integer, got Null

[wignoxqs]

This application has raised an unexpected
error and must abort.

[6] Type mismatch: wanted Integer, got Null instead.
FMain.?.0

- at input of invoice; data completed, "book the invoice"
- After changing the value in "value to remember" from a number to nothing (deleted content).
- also the Description was too long and got cut off but this has probably nothing to do with it