OH3: HTTP-Binding RegExp / JS

I tried to change the content of State Transformation with
JS:getBuedZemmerTemperature.js. (the js is stored in /etc/openhab/transform/)

and now I get the following errors :

2021-01-11 18:06:52.920 [INFO ] [nding.http.internal.HttpThingHandler] - Using the secure client for thing 'http:url:mobileAlerts'.
2021-01-11 18:06:52.922 [ERROR] [nal.common.AbstractInvocationHandler] - An error occurred while calling method 'ThingHandler.thingUpdated()' on 'org.openhab.binding.http.internal.HttpThingHandler@2561e5': The transformation pattern must consist of the type and the pattern separated by a colon
 java.lang.IllegalArgumentException: The transformation pattern must consist of the type and the pattern separated by a colon

Can any one help me in solving this, I am not a Java programmer, but a simple user.
Basoiically, I want to display the value returned in a dashboard as a temperature

Regards
Marc