Sketch running overnght, 243 lines of errors

Well, I assume they are errors.
Arduino 1.8.3, Ubuntu 16.04, Intel i5, 6GB, 256GB-SSD, 30-minute CyberPower-UPS, no screen saver etc

When I came in this morning, the IDE code-portion was all white. I did a page up and then down and it all came back. The Terminal was still running fine and reporting Serial stuff.

What does this all mean and what do I need to do to correct this? This is just the first 50 or so lines, but it repeated for a total so far of 243 lines and still going up.

Linux or Arduino?

Thanks

Exception in thread "AWT-EventQueue-0" java.lang.ClassCastException: sun.awt.image.BufImgSurfaceData cannot be cast to sun.java2d.xr.XRSurfaceData
	at sun.java2d.xr.XRPMBlitLoops.cacheToTmpSurface(XRPMBlitLoops.java:148)
	at sun.java2d.xr.XrSwToPMBlit.Blit(XRPMBlitLoops.java:356)
	at sun.java2d.pipe.DrawImage.blitSurfaceData(DrawImage.java:959)
	at sun.java2d.pipe.DrawImage.renderImageCopy(DrawImage.java:577)
	at sun.java2d.pipe.DrawImage.copyImage(DrawImage.java:67)
	at sun.java2d.pipe.DrawImage.copyImage(DrawImage.java:1014)
	at sun.java2d.SunGraphics2D.drawImage(SunGraphics2D.java:3318)
	at sun.java2d.SunGraphics2D.drawImage(SunGraphics2D.java:3296)
	at com.sun.java.swing.plaf.gtk.GTKEngine.paintCachedImage(GTKEngine.java:555)
	at com.sun.java.swing.plaf.gtk.GTKPainter.paintTextBackground(GTKPainter.java:944)
	at com.sun.java.swing.plaf.gtk.GTKPainter.paintLabelBackground(GTKPainter.java:234)
	at javax.swing.plaf.synth.SynthLabelUI.update(SynthLabelUI.java:174)
	at javax.swing.JComponent.paintComponent(JComponent.java:780)
	at javax.swing.JComponent.paint(JComponent.java:1056)
	at javax.swing.plaf.synth.SynthComboBoxUI$SynthComboBoxRenderer.paint(SynthComboBoxUI.java:511)
	at javax.swing.CellRendererPane.paintComponent(CellRendererPane.java:151)
	at javax.swing.plaf.synth.SynthComboBoxUI.paintCurrentValue(SynthComboBoxUI.java:404)
	at javax.swing.plaf.synth.SynthComboBoxUI.paint(SynthComboBoxUI.java:357)
	at javax.swing.plaf.synth.SynthComboBoxUI.update(SynthComboBoxUI.java:325)
	at javax.swing.JComponent.paintComponent(JComponent.java:780)
	at javax.swing.JComponent.paint(JComponent.java:1056)
	at javax.swing.JComponent.paintChildren(JComponent.java:889)
	at javax.swing.JComponent.paint(JComponent.java:1065)
	at javax.swing.JComponent.paintChildren(JComponent.java:889)
	at javax.swing.JComponent.paint(JComponent.java:1065)
	at javax.swing.JComponent.paintChildren(JComponent.java:889)
	at javax.swing.JComponent.paint(JComponent.java:1065)
	at javax.swing.JLayeredPane.paint(JLayeredPane.java:586)
	at javax.swing.JComponent.paintChildren(JComponent.java:889)
	at javax.swing.JComponent.paint(JComponent.java:1065)
	at javax.swing.JComponent.paintToOffscreen(JComponent.java:5210)
	at javax.swing.BufferStrategyPaintManager.paint(BufferStrategyPaintManager.java:290)
	at javax.swing.RepaintManager.paint(RepaintManager.java:1272)
	at javax.swing.JComponent._paintImmediately(JComponent.java:5158)
	at javax.swing.JComponent.paintImmediately(JComponent.java:4969)
	at javax.swing.RepaintManager$4.run(RepaintManager.java:854)
	at javax.swing.RepaintManager$4.run(RepaintManager.java:814)
	at java.security.AccessController.doPrivileged(Native Method)
	at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:80)
	at javax.swing.RepaintManager.paintDirtyRegions(RepaintManager.java:814)
	at javax.swing.RepaintManager.paintDirtyRegions(RepaintManager.java:789)
	at javax.swing.RepaintManager.prePaintDirtyRegions(RepaintManager.java:738)
	at javax.swing.RepaintManager.access$1200(RepaintManager.java:64)
	at javax.swing.RepaintManager$ProcessingRunnable.run(RepaintManager.java:1732)
	at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:311)
	at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:756)
	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:80)
	at java.awt.EventQueue.dispatchEvent(EventQueue.java:726)
	at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:201)
	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)
Exception in thread "AWT-EventQueue-0" java.lang.ClassCastException: sun.awt.image.BufImgSurfaceData cannot be cast to sun.java2d.xr.XRSurfaceData
	at sun.java2d.xr.XRPMBlitLoops.cacheToTmpSurface(XRPMBlitLoops.java:148)
	at sun.java2d.xr.XrSwToPMBlit.Blit(XRPMBlitLoops.java:356)
	at sun.java2d.SurfaceDataProxy.updateSurfaceData(SurfaceDataProxy.java:498)
	at sun.java2d.SurfaceDataProxy.replaceData(SurfaceDataProxy.java:455)
	at sun.java2d.SurfaceData.getSourceSurfaceData(SurfaceData.java:233)