From 893f95eed8534f0ba137660ce13a161b4468d3d0 Mon Sep 17 00:00:00 2001
From: David Edmundson <kde@davidedmundson.co.uk>
Date: Thu, 1 Jul 2021 12:38:57 +0100
Subject: [PATCH] Guard against null compositor in thumbnail item

If compositing is disabled, compositor will be null.

We hit a path where we could destroyOffscreenTexture when the
compositing is disabled then again when the Thumbnail is destroyed. In
this case we query Compositor::self()->scene() and crash.
---
 src/scripting/thumbnailitem.cpp | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/src/scripting/thumbnailitem.cpp b/src/scripting/thumbnailitem.cpp
index 58879a9d57..61bdc35514 100644
--- a/src/scripting/thumbnailitem.cpp
+++ b/src/scripting/thumbnailitem.cpp
@@ -145,6 +145,9 @@ QSGTextureProvider *ThumbnailItemBase::textureProvider() const
 
 void ThumbnailItemBase::handleCompositingToggled()
 {
+    if (!Compositor::self()) {
+        return;
+    }
     Scene *scene = Compositor::self()->scene();
     if (scene && scene->compositingType() == OpenGLCompositing) {
         connect(scene, &Scene::frameRendered, this, &ThumbnailItemBase::updateOffscreenTexture);
@@ -167,6 +170,9 @@ void ThumbnailItemBase::setSourceSize(const QSize &sourceSize)
 
 void ThumbnailItemBase::destroyOffscreenTexture()
 {
+    if (!Compositor::self()) {
+        return;
+    }
     Scene *scene = Compositor::self()->scene();
     if (!scene || scene->compositingType() != OpenGLCompositing) {
         return;