[GREENFOOT-752] AbsentInformationException is fired

Got an AbsentInformationException in the debug log. Not totally sure about the cause, will try to reproduce: {quote}Internal error: could not get local variable info:

{{com.sun.tools.jdi.NonConcreteMethodImpl.variables(NonConcreteMethodImpl.java:94)}}

{{bluej.debugmgr.ExecControls.setStackFrameDetails(ExecControls.java:455)}}

{{bluej.utility.javafx.JavaFXUtil.lambda$addChangeListenerPlatform$26(JavaFXUtil.java:1508)}}

{{bluej.pkgmgr.Project.lambda$threadStateChanged$9(Project.java:2510)}} {quote}

Issue metadata

Issue type: Bug
Priority: Medium