[Bug]: IDE Internal error - An editable copy of Default has not been initialized

[aquatix]

Describe the bug

Thanks for making these beautiful themes!

On starting my PyCharm 2026.1.2 I was greeted with a notification pop-up about an IDE error, which turned out to be caused by the theme:

java.lang.Throwable: An editable copy of Default has not been initialized.
	at com.intellij.openapi.diagnostic.Logger.error(Logger.java:375)
	at com.intellij.openapi.editor.colors.impl.EditorColorsManagerImpl.getEditableDefaultScheme(EditorColorsManagerImpl.kt:409)
	at com.intellij.openapi.editor.colors.impl.EditorColorsManagerImpl.getGlobalScheme(EditorColorsManagerImpl.kt:384)
	at com.mallowigi.idea.tabs.painters.MTTabsPainter.getTabUnderlineColor(MTTabsPainter.kt:255)
	at com.mallowigi.idea.tabs.painters.MTTabsPainter.paintUnderline(MTTabsPainter.kt:159)
	at com.intellij.ui.tabs.impl.JBEditorTabsBorder.paintBorder(JBEditorTabsBorder.kt:130)
	at com.intellij.ui.tabs.impl.JBTabsImpl.drawBorder(JBTabsImpl.kt:2443)
	at com.intellij.ui.tabs.impl.JBTabsImpl.paintComponent(JBTabsImpl.kt:2371)
	at java.desktop/javax.swing.JComponent.paint(JComponent.java:1124)
	at java.desktop/javax.swing.JComponent.paintChildren(JComponent.java:964)
	at java.desktop/javax.swing.JComponent.paint(JComponent.java:1133)
	at java.desktop/javax.swing.JComponent.paintChildren(JComponent.java:964)
	at com.intellij.openapi.fileEditor.impl.EditorsSplitters.paintChildren(EditorsSplitters.kt:341)
	at java.desktop/javax.swing.JComponent.paint(JComponent.java:1133)
	at java.desktop/javax.swing.JComponent.paintToOffscreen(JComponent.java:5325)
	at java.desktop/javax.swing.BufferStrategyPaintManager.paint(BufferStrategyPaintManager.java:256)
	at java.desktop/javax.swing.RepaintManager.paint(RepaintManager.java:1297)
	at java.desktop/javax.swing.JComponent._paintImmediately(JComponent.java:5273)
	at java.desktop/javax.swing.JComponent.paintImmediately(JComponent.java:5083)
	at java.desktop/javax.swing.JComponent.paintImmediately(JComponent.java:5064)
	at java.desktop/javax.swing.RepaintManager.paintDirtyRegions(RepaintManager.java:836)
	at java.desktop/javax.swing.RepaintManager.paintDirtyRegions(RepaintManager.java:799)
	at java.desktop/javax.swing.RepaintManager.prePaintDirtyRegions(RepaintManager.java:739)
	at java.desktop/javax.swing.RepaintManager$ProcessingRunnable.run(RepaintManager.java:1866)
	at com.intellij.util.concurrency.ChildContext$runInChildContext$1.invoke(propagation.kt:192)
	at com.intellij.util.concurrency.ChildContext$runInChildContext$1.invoke(propagation.kt:192)
	at com.intellij.util.concurrency.ChildContext.runInChildContext(propagation.kt:198)
	at com.intellij.util.concurrency.ChildContext.runInChildContext(propagation.kt:192)
	at com.intellij.util.concurrency.ContextRunnable.lambda$run$0(ContextRunnable.java:26)
	at com.intellij.concurrency.ThreadContext.resetThreadContext(threadContext.kt:294)
	at com.intellij.util.concurrency.ContextRunnable.run(ContextRunnable.java:25)
	at java.desktop/java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:323)
	at java.desktop/java.awt.EventQueue.dispatchEventImpl(EventQueue.java:732)
	at java.desktop/java.awt.EventQueue.dispatchEvent(EventQueue.java:711)
	at com.intellij.ide.IdeEventQueue.defaultDispatchEvent(IdeEventQueue.kt:721)
	at com.intellij.ide.IdeEventQueue._dispatchEvent(IdeEventQueue.kt:574)
	at com.intellij.ide.IdeEventQueue.dispatchEvent$lambda$0$0$0$0(IdeEventQueue.kt:382)
	at com.intellij.openapi.progress.impl.CoreProgressManager.computePrioritized(CoreProgressManager.java:928)
	at com.intellij.ide.IdeEventQueue.dispatchEvent$lambda$0$0$0(IdeEventQueue.kt:381)
	at com.intellij.ide.IdeEventQueueKt.performActivity$lambda$0(IdeEventQueue.kt:1111)
	at com.intellij.openapi.application.TransactionGuardImpl.performActivity(TransactionGuardImpl.java:106)
	at com.intellij.ide.IdeEventQueueKt.performActivity(IdeEventQueue.kt:1111)
	at com.intellij.ide.IdeEventQueue.dispatchEvent$lambda$0(IdeEventQueue.kt:376)
	at com.intellij.ide.IdeEventQueue.dispatchEvent(IdeEventQueue.kt:408)
	at java.desktop/java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:207)
	at java.desktop/java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:128)
	at java.desktop/java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:117)
	at java.desktop/java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:113)
	at java.desktop/java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:105)
	at java.desktop/java.awt.EventDispatchThread.run(EventDispatchThread.java:92)

Let me know how I can help!

To Reproduce

1. Enable Material Theme UI
2. Choose Material Darker (possibly any theme?)
3. Close PyCharm
4. Launch PyCharm
5. Observe a red notification by PyCharm/IDEA about an internal IDE error

Expected behavior

Do not have that stacktrace :)

Material Theme Version

11.1.0

IDE

PyCharm

System Info

PyCharm 2026.1.2
Build #PY-261.24374.152, built on May 15, 2026
Source revision: de528ed045cf1
Licensed to (me)
Subscription is active until July 31, 2026.
Runtime version: 25.0.2+10-b329.117 amd64137.0.17-261-b81
VM: OpenJDK 64-Bit Server VM by JetBrains s.r.o.
Toolkit: sun.awt.wl.WLToolkit
Linux 7.0.0-22-generic
Ubuntu 26.04 LTS; glibc: 2.43; desktop: GNOME (GNOME Shell 50.1)
Exception reporter ID: 11022531dc9e482-08c5-4a0f-a074-bce49377b17c
GC: G1 Young Generation, G1 Concurrent GC, G1 Old Generation
Memory: 3976M
Cores: 8
Registry:
  debugger.new.tool.window.layout=true
  ide.experimental.ui=true
  editor.ux.survey.enabled=false
  python.debug.low.impact.monitoring.api=false
  trace.state.event.service.url=https://api.jetbrains.cloud/trace-status
Non-Bundled Plugins:
  com.jetbrains.performancePlugin (261.24374.171)
  IdeaVIM (2.37.0)
  XPathView (261.23567.28)
  ru.adelf.idea.dotenv (261.24374.154)
  hg4idea (261.23567.28)
  org.jetbrains.security.package-checker (261.24374.34)
  com.andrey4623.rainbowcsv (2.0.2)
  mobi.hsz.idea.gitignore (4.5.7)
  com.mallowigi (201.0.1)
  net.ashald.envfile (5.0.1)
  com.intellij.mermaid (0.0.27+IJ.253)
  String Manipulation (9.16.0)
  org.jetbrains.dbt (261.22158.182)
  org.jetbrains.plugins.vue (261.24374.154)
  com.dmarcotte.handlebars (261.22158.180)
  mdx.js (261.22158.185)
  izhangzhihao.rainbow.brackets.lite (1.3.0)
  com.koxudaxi.pydantic (0.4.24)
  com.chrisrm.idea.MaterialThemeUI (11.1.0)
  com.jetbrains.space (261.24374.30)
  com.intellij.ideolog (261.22158.195)
Current Desktop: GNOME

Logs/Screenshots