From 339e4e3526ec265d2ca897640e07df46fa3969bc Mon Sep 17 00:00:00 2001
From: Bill Arbuckle <wfainc@gmail.com>
Date: Sat, 4 Apr 2026 18:04:01 -0500
Subject: [PATCH] Guard background messaging and detection

---
 background/detect.js   |  4 ++++
 background/messages.js | 14 +++++++++++++-
 2 files changed, 17 insertions(+), 1 deletion(-)

diff --git a/background/detect.js b/background/detect.js
index ab3bff9..f47aecf 100644
--- a/background/detect.js
+++ b/background/detect.js
@@ -79,6 +79,10 @@ md.detect = ({storage: {state}, inject}) => {
   }
 
   var detect = (content, url) => {
+    if (!url || !state.origins) {
+      return
+    }
+
     var location = new URL(url)
 
     var origin =
diff --git a/background/messages.js b/background/messages.js
index 14a1603..81471c1 100644
--- a/background/messages.js
+++ b/background/messages.js
@@ -165,7 +165,19 @@ md.messages = ({storage: {defaults, state, set}, compilers, mathjax, xhr, webreq
 
   function notifyContent (req, res) {
     chrome.tabs.query({active: true, currentWindow: true}, (tabs) => {
-      chrome.tabs.sendMessage(tabs[0].id, req, res)
+      if (!tabs.length) {
+        res && res()
+        return
+      }
+
+      chrome.tabs.sendMessage(tabs[0].id, req, (response) => {
+        if (chrome.runtime.lastError) {
+          res && res()
+          return
+        }
+
+        res && res(response)
+      })
     })
   }
 }