Variable declaration in groovy 3

[fernando88to]

When I declare in groovy 3 a variable like this

def x

the following message is displayed

Task :cloverInstrumentCodeForTest FAILED [ant:clover-setup] Clover-for-Groovy failed to instrument Groovy source: /home/fernando/IdeaProjects/grailsci/grails-app/controllers/com/fernando/IndexController.groovy java.lang.RuntimeException: Clover-for-Groovy failed to instrument Groovy source: /home/fernando/IdeaProjects/grailsci/grails-app/controllers/com/fernando/IndexController.groovy

Now when I switch to

def x = null

It works perfectly

Tools version
Groovy 3
org.openclover:clover:4.4.1