NullPointerException: Cannot read field "width" because "this.componentInnards" is null

Created by: benfry

Seen in 4.0, but not clear if this is downstream problems caused by https://github.com/processing/processing4/issues/530 or if it's an error triggered by changing between themes.

Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException: Cannot read field "width" because "this.componentInnards" is null
at java.desktop/javax.swing.plaf.basic.BasicProgressBarUI.updateSizes(BasicProgressBarUI.java:542)
at java.desktop/javax.swing.plaf.basic.BasicProgressBarUI.getBox(BasicProgressBarUI.java:499)
at java.desktop/javax.swing.plaf.basic.BasicProgressBarUI.paintIndeterminate(BasicProgressBarUI.java:656)
at java.desktop/javax.swing.plaf.basic.BasicProgressBarUI.paint(BasicProgressBarUI.java:464)
at java.desktop/javax.swing.plaf.ComponentUI.update(ComponentUI.java:161)
at java.desktop/javax.swing.JComponent.paintComponent(JComponent.java:842)
at java.desktop/javax.swing.JComponent.paint(JComponent.java:1119)
at java.desktop/javax.swing.JComponent.paintToOffscreen(JComponent.java:5311)
at java.desktop/javax.swing.RepaintManager$PaintManager.paintDoubleBufferedImpl(RepaintManager.java:1657)
at java.desktop/javax.swing.RepaintManager$PaintManager.paintDoubleBuffered(RepaintManager.java:1632)
at java.desktop/javax.swing.RepaintManager$PaintManager.paint(RepaintManager.java:1570)
at java.desktop/javax.swing.RepaintManager.paint(RepaintManager.java:1337)
at java.desktop/javax.swing.JComponent._paintImmediately(JComponent.java:5259)
at java.desktop/javax.swing.JComponent.paintImmediately(JComponent.java:5069)
at java.desktop/javax.swing.RepaintManager$4.run(RepaintManager.java:879)
at java.desktop/javax.swing.RepaintManager$4.run(RepaintManager.java:862)
at java.base/java.security.AccessController.doPrivileged(AccessController.java:399)
at java.base/java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:86)
at java.desktop/javax.swing.RepaintManager.paintDirtyRegions(RepaintManager.java:862)
at java.desktop/javax.swing.RepaintManager.paintDirtyRegions(RepaintManager.java:835)
at java.desktop/javax.swing.RepaintManager.prePaintDirtyRegions(RepaintManager.java:784)
at java.desktop/javax.swing.RepaintManager$ProcessingRunnable.run(RepaintManager.java:1898)
at java.desktop/java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:318)
at java.desktop/java.awt.EventQueue.dispatchEventImpl(EventQueue.java:771)
at java.desktop/java.awt.EventQueue$4.run(EventQueue.java:722)
at java.desktop/java.awt.EventQueue$4.run(EventQueue.java:716)
at java.base/java.security.AccessController.doPrivileged(AccessController.java:399)
at java.base/java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:86)
at java.desktop/java.awt.EventQueue.dispatchEvent(EventQueue.java:741)
at java.desktop/java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:203)
at java.desktop/java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:124)
at java.desktop/java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:113)
at java.desktop/java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:109)
at java.desktop/java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:101)
at java.desktop/java.awt.EventDispatchThread.run(EventDispatchThread.java:90)

まずテーマを変更したときの Processing 4 での失敗を再現し、次に BasicProgressBarUI のスタックトレースに示されているプログレスバーの描画経路を追跡します。processing4#530 にある可能性のある下流の問題と動作を比較します。テーマを変更してもこの NullPointerException が発生しなくなれば完了です。