Fix NullReferenceException when unregistering folding manager after t…

…he document was detached from the TextArea.
icsharpcode · Dec 19, 2019 · b070099 · b070099
1 parent b98689a
commit b070099
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Showing 2 changed files with 10 additions and 2 deletions.
diff --git a/ICSharpCode.AvalonEdit/Rendering/CollapsedLineSection.cs b/ICSharpCode.AvalonEdit/Rendering/CollapsedLineSection.cs
@@ -86,10 +86,12 @@ public void Uncollapse()
 			if (start == null)
 				return;
 
-			heightTree.Uncollapse(this);
+			if (!heightTree.IsDisposed) {
+				heightTree.Uncollapse(this);
 #if DEBUG
-			heightTree.CheckProperties();
+				heightTree.CheckProperties();
 #endif
+			}
 
 			start = null;
 			end = null;

diff --git a/ICSharpCode.AvalonEdit/Rendering/HeightTree.cs b/ICSharpCode.AvalonEdit/Rendering/HeightTree.cs
@@ -73,6 +73,12 @@ public void Dispose()
 			this.weakLineTracker = null;
 		}
 
+		public bool IsDisposed {
+			get {
+				return root == null;
+			}
+		}
+
 		double defaultLineHeight;
 
 		public double DefaultLineHeight {