From ed68bbec549dedeb89bcb584151b097863b52d0d Mon Sep 17 00:00:00 2001
From: bobzel <zzzman@gmail.com>
Date: Thu, 14 Oct 2021 12:16:17 -0400
Subject: fixed comparison box error.

---
 src/client/views/nodes/ComparisonBox.tsx | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

(limited to 'src')

diff --git a/src/client/views/nodes/ComparisonBox.tsx b/src/client/views/nodes/ComparisonBox.tsx
index b1aada158..0f962f95c 100644
--- a/src/client/views/nodes/ComparisonBox.tsx
+++ b/src/client/views/nodes/ComparisonBox.tsx
@@ -90,7 +90,7 @@ export class ComparisonBox extends ViewBoxAnnotatableComponent<ViewBoxAnnotatabl
         const displayDoc = (which: string) => {
             var whichDoc = Cast(this.dataDoc[which], Doc, null);
             //if (whichDoc?.type === DocumentType.MARKER) 
-            const targetDoc = Cast(whichDoc.annotationOn, Doc, null) ?? whichDoc;
+            const targetDoc = Cast(whichDoc?.annotationOn, Doc, null) ?? whichDoc;
             return whichDoc ? <>
                 <DocumentView
                     ref={(r) => {
-- 
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