From ff63ec97b75706b7e12442c7c814e96c89f2db55 Mon Sep 17 00:00:00 2001
From: Sascha Buehrle <47737812+saschabuehrle@users.noreply.github.com>
Date: Mon, 23 Mar 2026 13:26:09 +0100
Subject: [PATCH] fix: return empty output for zero-length To Modhex input
 (#2249)

---
 src/core/lib/Modhex.mjs           |  2 ++
 tests/operations/tests/Modhex.mjs | 20 ++++++++++++++++++++
 2 files changed, 22 insertions(+)

diff --git a/src/core/lib/Modhex.mjs b/src/core/lib/Modhex.mjs
index 4f28e9a11..ab4a7c8bb 100644
--- a/src/core/lib/Modhex.mjs
+++ b/src/core/lib/Modhex.mjs
@@ -50,6 +50,7 @@ const HEX_ALPHABET_MAP = HEX_ALPHABET.split("");
 export function toModhex(data, delim=" ", padding=2, extraDelim="", lineSize=0) {
     if (!data) return "";
     if (data instanceof ArrayBuffer) data = new Uint8Array(data);
+    if (data.length === 0) return "";
 
     const regularHexString = toHex(data, "", padding, "", 0);
 
@@ -100,6 +101,7 @@ export function toModhex(data, delim=" ", padding=2, extraDelim="", lineSize=0)
 export function toModhexFast(data) {
     if (!data) return "";
     if (data instanceof ArrayBuffer) data = new Uint8Array(data);
+    if (data.length === 0) return "";
 
     const output = [];
 
diff --git a/tests/operations/tests/Modhex.mjs b/tests/operations/tests/Modhex.mjs
index 1e0f27912..07f38910c 100644
--- a/tests/operations/tests/Modhex.mjs
+++ b/tests/operations/tests/Modhex.mjs
@@ -147,4 +147,24 @@ dc;ii;hv;ig;hr;hf;dc;he;hj;hv;hv;ie;hg;du",
             }
         ]
     },
+    {
+        name: "Empty input through From Hex and To Modhex returns empty output",
+        input: "",
+        expectedOutput: "",
+        recipeConfig: [
+            {
+                "op": "From Hex",
+                "args": [
+                    "Auto"
+                ]
+            },
+            {
+                "op": "To Modhex",
+                "args": [
+                    "Space",
+                    0
+                ]
+            }
+        ]
+    },
 ]);