From 9134c11cf8dcf2c2a515e7a6d8983ee6b0d42858 Mon Sep 17 00:00:00 2001
From: Raymond Hill <rhill@raymondhill.net>
Date: Tue, 23 May 2023 21:49:42 -0400
Subject: [PATCH] Fix https://github.com/uBlockOrigin/uBlock-issues/issues/2668

Use document.append() only when there are no elements in
the DOM, as a document instance can't have more than one
direct child.
---
 platform/firefox/vapi-background-ext.js | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/platform/firefox/vapi-background-ext.js b/platform/firefox/vapi-background-ext.js
index cfa0d5900..72d2e1d37 100644
--- a/platform/firefox/vapi-background-ext.js
+++ b/platform/firefox/vapi-background-ext.js
@@ -315,7 +315,7 @@ vAPI.scriptletsInjector = ((doc, details) => {
         script = doc.createElement('script');
         script.async = false;
         script.src = url;
-        doc.append(script);
+        (doc.head || doc.documentElement || doc).append(script);
         self.uBO_scriptletsInjected = details.filters;
     } catch (ex) {
     }