From 917a92cf34849c1db9e3c0d733bfec2877984111 Mon Sep 17 00:00:00 2001
From: SharkyKZ <sharkykz@gmail.com>
Date: Fri, 2 Oct 2020 20:27:46 +0300
Subject: [PATCH] [4.0] Fall back to system template when template file not
 found (#30857)

* Fall back to system template

* Load parent language file only when needed

* Correct template file
---
 libraries/src/Document/HtmlDocument.php | 30 ++++++++++++-------------
 1 file changed, 15 insertions(+), 15 deletions(-)

diff --git a/libraries/src/Document/HtmlDocument.php b/libraries/src/Document/HtmlDocument.php
index 1cc28b52d6c5c..3e5bf5f538222 100644
--- a/libraries/src/Document/HtmlDocument.php
+++ b/libraries/src/Document/HtmlDocument.php
@@ -827,22 +827,22 @@ protected function _fetchTemplate($params = array())
 		$inherits = $params['templateInherits'] ?? '';
 		$baseDir = $directory . '/' . $template;
 
-		if (!empty($inherits)
-			&& !is_file($directory . '/' . $template . '/' . $file)
-			&& is_file($directory . '/' . $inherits . '/' . $file)
-		)
+		if (!is_file($directory . '/' . $template . '/' . $file))
 		{
-			$baseDir = $directory . '/' . $inherits;
-		}
-
-		if (!is_file($baseDir . '/' . $file))
-		{
-			$template = 'system';
-		}
+			if ($inherits !== '' && is_file($directory . '/' . $inherits . '/' . $file))
+			{
+				$baseDir = $directory . '/' . $inherits;
+			}
+			else
+			{
+				$baseDir  = $directory . '/system';
+				$template = 'system';
 
-		if (!is_file($baseDir . '/' . $file))
-		{
-			$file = 'index.php';
+				if ($file !== 'index.php' && !is_file($baseDir . '/' . $file))
+				{
+					$file = 'index.php';
+				}
+			}
 		}
 
 		// Load the language file for the template
@@ -850,7 +850,7 @@ protected function _fetchTemplate($params = array())
 
 		// 1.5 or core then 1.6
 		$lang->load('tpl_' . $template, JPATH_BASE)
-			|| $lang->load('tpl_' . $inherits, $directory . '/' . $inherits)
+			|| ($inherits !== '' && $lang->load('tpl_' . $inherits, $directory . '/' . $inherits))
 			|| $lang->load('tpl_' . $template, $directory . '/' . $template);
 
 		// Assign the variables