From 0c7e06a10c7196c24210afda2e43aa3f26d6dcbc Mon Sep 17 00:00:00 2001
From: "jeremy@jermolene.com" <jeremy@jermolene.com>
Date: Fri, 3 Mar 2023 18:22:35 +0000
Subject: [PATCH] Fix crash with invalid patches

See https://github.com/Jermolene/TiddlyWiki5/pull/7290#issuecomment-1453155311

Thanks @yaisog
---
 core/modules/filters/strings.js               | 10 ++++++++-
 .../tests/data/filters/DiffMergePatch3.tid    | 22 +++++++++++++++++++
 2 files changed, 31 insertions(+), 1 deletion(-)
 create mode 100644 editions/test/tiddlers/tests/data/filters/DiffMergePatch3.tid

diff --git a/core/modules/filters/strings.js b/core/modules/filters/strings.js
index 30881880c..1e015ff46 100644
--- a/core/modules/filters/strings.js
+++ b/core/modules/filters/strings.js
@@ -95,8 +95,16 @@ exports.makepatches = makeStringBinaryOperator(
 exports.applypatches = makeStringBinaryOperator(
 	function(a,b) {
 		var dmpObject = new dmp.diff_match_patch(),
+			patches;
+		try {
 			patches = dmpObject.patch_fromText(b);
-		return [dmpObject.patch_apply(patches,a)[0]];
+		} catch(e) {
+		}
+		if(patches) {
+			return [dmpObject.patch_apply(patches,a)[0]];
+		} else {
+			return [a];
+		}
 	}
 );
 
diff --git a/editions/test/tiddlers/tests/data/filters/DiffMergePatch3.tid b/editions/test/tiddlers/tests/data/filters/DiffMergePatch3.tid
new file mode 100644
index 000000000..87d98e890
--- /dev/null
+++ b/editions/test/tiddlers/tests/data/filters/DiffMergePatch3.tid
@@ -0,0 +1,22 @@
+title: Filters/DiffMergePatch3
+description: Tests for diff-merge-patch derived operators
+type: text/vnd.tiddlywiki-multiple
+tags: [[$:/tags/wiki-test-spec]]
+
+title: Output
+
+\whitespace trim
+\define text1()
+the cat sat on the mat
+\end
+
+\define patches()
+**NOT A VALID PATCH**
+\end
+
+<$text text={{{ [<text1>applypatches<patches>] }}}/>
+
++
+title: ExpectedResult
+
+the cat sat on the mat
\ No newline at end of file