Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
at com.barrybecker4.simulation.waveFunctionCollapse.model.wave.Wave.doPropagation(Wave.scala:147)
at com.barrybecker4.simulation.waveFunctionCollapse.model.wave.Wave.propagate(Wave.scala:139)
at com.barrybecker4.simulation.waveFunctionCollapse.model.WfcModel.$anonfun$advance$2(WfcModel.scala:65)
at scala.collection.immutable.Range.foreach$mVc$sp(Range.scala:190)
at com.barrybecker4.simulation.waveFunctionCollapse.model.WfcModel.advance(WfcModel.scala:59)
at com.barrybecker4.simulation.waveFunctionCollapse.model.WfcModel.runWithLimit(WfcModel.scala:43)
at com.barrybecker4.simulation.waveFunctionCollapse.model.WfcModel.startRun(WfcModel.scala:49)
at com.barrybecker4.simulation.waveFunctionCollapse.DynamicOptions.runModel(DynamicOptions.scala:248)
at com.barrybecker4.simulation.waveFunctionCollapse.DynamicOptions.itemStateChanged(DynamicOptions.scala:261)
at java.desktop/javax.swing.JComboBox.fireItemStateChanged(JComboBox.java:1227)
at java.desktop/javax.swing.JComboBox.selectedItemChanged(JComboBox.java:1279)
I often get a stack trace like this