From 9323caf2f16ffc4812ff6c9717555f696e1b81a8 Mon Sep 17 00:00:00 2001
From: Laurent Cozic <laurent@cozic.net>
Date: Sun, 20 Jun 2021 13:59:58 +0100
Subject: [PATCH] Fixed revision issue for old revisions

---
 packages/lib/models/Revision.ts | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/packages/lib/models/Revision.ts b/packages/lib/models/Revision.ts
index 11ff38045..57d6c708e 100644
--- a/packages/lib/models/Revision.ts
+++ b/packages/lib/models/Revision.ts
@@ -45,7 +45,10 @@ export default class Revision extends BaseItem {
 		if (this.isLegacyPatch(patch)) {
 			return this.applyTextPatchLegacy(text, patch);
 		} else {
-			const result = dmp.patch_apply(JSON.parse(patch), text);
+			// An empty patch should be '[]', but legacy data may be just "".
+			// However an empty string would make JSON.parse fail so we set it
+			// to '[]'.
+			const result = dmp.patch_apply(JSON.parse(patch ? patch : '[]'), text);
 			if (!result || !result.length) throw new Error('Could not apply patch');
 			return result[0];
 		}