Ideal Graph Visualizer throws the following exception error when drawing a relatively large graph (see screenshot attached):

java.lang.AssertionError: duplicate : Node 3355 [bci=69 11, debug_idx=14103355, dump_spec=#java/nio/file/Path:NotNull * Interface:java/nio/file/Path:NotNull *, id=3355, idx=3355, line=83, name=CastPP, type=inst:]
at com.sun.hotspot.igv.data.InputBlock.addNode(InputBlock.java:95)
at com.sun.hotspot.igv.data.InputGraph.ensureNodesInBlocks(InputGraph.java:173)
at com.sun.hotspot.igv.view.DiagramScene.update(DiagramScene.java:522)
at com.sun.hotspot.igv.view.DiagramScene.setNewModel(DiagramScene.java:502)
at com.sun.hotspot.igv.view.DiagramScene.<init>(DiagramScene.java:442)
at com.sun.hotspot.igv.view.EditorTopComponent.<init>(EditorTopComponent.java:210)
at com.sun.hotspot.igv.view.GraphViewerImplementation.view(GraphViewerImplementation.java:60)
at com.sun.hotspot.igv.coordinator.actions.GraphOpenCookie.open(GraphOpenCookie.java:42)
at org.openide.actions.OpenAction.performAction(OpenAction.java:84)
at org.openide.util.actions.NodeAction$DelegateAction$1.run(NodeAction.java:586)
at org.openide.util.actions.ActionInvoker$1.run(ActionInvoker.java:95)
at org.openide.util.actions.ActionInvoker.doPerformAction(ActionInvoker.java:116)
at org.openide.util.actions.ActionInvoker.invokeAction(ActionInvoker.java:99)
at org.openide.util.actions.NodeAction$DelegateAction.actionPerformed(NodeAction.java:583)
at org.openide.explorer.view.TreeView$PopupSupport.mouseClicked(TreeView.java:1625)
at java.awt.AWTEventMulticaster.mouseClicked(AWTEventMulticaster.java:270)
at java.awt.AWTEventMulticaster.mouseClicked(AWTEventMulticaster.java:269)
at java.awt.AWTEventMulticaster.mouseClicked(AWTEventMulticaster.java:269)
at java.awt.AWTEventMulticaster.mouseClicked(AWTEventMulticaster.java:269)
at java.awt.Component.processMouseEvent(Component.java:6542)
at javax.swing.JComponent.processMouseEvent(JComponent.java:3324)
at java.awt.Component.processEvent(Component.java:6304)
at java.awt.Container.processEvent(Container.java:2239)
at java.awt.Component.dispatchEventImpl(Component.java:4889)
at java.awt.Container.dispatchEventImpl(Container.java:2297)
at java.awt.Component.dispatchEvent(Component.java:4711)
at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4904)
at java.awt.LightweightDispatcher.processMouseEvent(Container.java:4544)
at java.awt.LightweightDispatcher.dispatchEvent(Container.java:4476)
at java.awt.Container.dispatchEventImpl(Container.java:2283)
at java.awt.Window.dispatchEventImpl(Window.java:2746)
at java.awt.Component.dispatchEvent(Component.java:4711)
at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:760)
at java.awt.EventQueue.access$500(EventQueue.java:97)
at java.awt.EventQueue$3.run(EventQueue.java:709)
at java.awt.EventQueue$3.run(EventQueue.java:703)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:74)
at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:84)
at java.awt.EventQueue$4.run(EventQueue.java:733)
at java.awt.EventQueue$4.run(EventQueue.java:731)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:74)
at java.awt.EventQueue.dispatchEvent(EventQueue.java:730)
at org.netbeans.core.TimableEventQueue.dispatchEvent(TimableEventQueue.java:159)
[catch] at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:205)
at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:116)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:105)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:101)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:93)
at java.awt.EventDispatchThread.run(EventDispatchThread.java:82)

The assertion error indicates that the same node is being added twice to a basic block when computing the approximated CFG.

STEPS TO REPRODUCE:

1. $ cd src/utils/IdealGraphVisualizer
2. $ export JAVA_HOME=... (JDK 8)
3. $ ant build
4. $ sh igv.sh
5. $ java -Xbatch -XX:CompileCommand=IGVPrintLevel,java.nio.file.FileTreeIterator::fetchNextIfNeeded,1 -XX:CompileCommand=compileonly,java.nio.file.FileTreeIterator::fetchNextIfNeeded HelloWorld.java
6. Go to IdealGraphVisualizer window, expand the first method "virtual void java.nio.file.FileTreeIterator::fetchNextIfNeeded()"
7. Double-click on "Before matching"
8. After a few seconds, the exception is triggered

The Ideal Graph Visualizer runs on the following JDK version:

$JAVA_HOME/bin/java -version
java version "1.8.0_261"
Java(TM) SE Runtime Environment (build 1.8.0_261-b12)
Java HotSpot(TM) 64-Bit Server VM (build 25.261-b12, mixed mode)