Exception in genModelEditor UI with GMA extensions

[opcoach]

When the GenModelEditor is displayed using the GMA objects (extension of genModel objects), it generates this exception on a right click :

It seems that genmodeladdon.ui would provide property tester for the new objects

!ENTRY org.eclipse.e4.ui.workbench 4 0 2019-07-04 23:53:48.903
!MESSAGE Failed to evaluate: WithExpression [variable=activeMenuSelection, children=[IterateExpression [type=OR, children=[, ]]]]
!STACK 0
org.eclipse.core.runtime.CoreException: No property tester contributes a property org.eclipse.emf.ecp.core.project.open to type class com.opcoach.genmodeladdon.core.genmodel.impl.GMAGenClassImpl
at org.eclipse.core.internal.expressions.TypeExtensionManager.getProperty(TypeExtensionManager.java:130)
at org.eclipse.core.internal.expressions.TestExpression.evaluate(TestExpression.java:100)
at org.eclipse.core.internal.expressions.CompositeExpression.evaluateAnd(CompositeExpression.java:55)
at org.eclipse.core.internal.expressions.IterateExpression.evaluate(IterateExpression.java:199)
at org.eclipse.core.internal.expressions.CompositeExpression.evaluateAnd(CompositeExpression.java:55)
at org.eclipse.core.internal.expressions.WithExpression.evaluate(WithExpression.java:81)
at org.eclipse.ui.internal.services.EvaluationReference.evaluate(EvaluationReference.java:74)