String with placeholder sends wrong output on missing value

[Hypnos3]

With the placeholder L=${payload},L2=${slat}:

• after deploy the nodes sends L=,L2=
• with a level of 5 slat of 0 the nodes sends L=5,L2=
• with a level and slat > 0 all worky as needed.

source: https://homematic-forum.de/forum/viewtopic.php?p=704039#p704039

Requested: stringWith placeholder should send every time a valid value!

[Hypnos3]

Aktuell Zeitsteuerung über Regel Nr.6 von bürgerlicher Abenddämmerung
Behang = 0
Slat = 0

Ergebnis Debug Node =

autoTrigger/triggerOnly/start : msg.payload : string[6]
"L=,L2="

gefolgt von CCU Unverständnis ....

msg : string[58]
" < HmIP-RF setValue Error: XML-RPC fault: Generic error"
2.2.2022, 19:55:53node: 14865d333973150emsg : string[111]
"rpc > HmIP-RF setValue ["xxxxxxxxxxxx:4","COMBINED_PARAMETER","L=,L2="] < Error: XML-RPC fault: Generic error"
2.2.2022, 19:55:53node: WZ-Süd-Rollladen
msg : error
"Error: XML-RPC fault: Generic error

gleiche Regel nur
Behang = 1
Slat = 1

autoTrigger/triggerOnly/start : msg.payload : string[8]
"L=1,L2=1"

[Hypnos3]

fixed with 2.0.13