Bug-fix.

Changelog excerpt:
- Some browsers, in some contexts, were raising errors during request
  inspection concerning the absence of any X-Content-Type-Options header
  declaration (though it isn't entirely clear whether this error had any
  actual effect); Fixed.

Author: Maikuolan

Changelog.md

@@ -198,6 +198,7 @@ __*Why "v3.0.0" instead of "v1.0.0?"*__ Prior to phpMussel v3, the "phpMussel Co
 
 #### Bugs fixed.
 - [2025.07.07]: The formatFilesize method wasn't accounting for negative numbers; Fixed.
+- [2025.07.26]: Some browsers, in some contexts, were raising errors during request inspection concerning the absence of any X-Content-Type-Options header declaration (though it isn't entirely clear whether this error had any actual effect); Fixed.
 
 #### Other changes.
 - [2025.07.05]: Aesthetic patch.

src/FrontEnd.php

@@ -8,7 +8,7 @@
  * License: GNU/GPLv2
  * @see LICENSE.txt
  *
- * This file: Front-end handler (last modified: 2025.07.07).
+ * This file: Front-end handler (last modified: 2025.07.26).
  */
 
 namespace phpMussel\FrontEnd;
@@ -1588,6 +1588,7 @@ private function eTaggable(string $Asset, ?callable $Callback = null): void
             $ThisAsset = $this->getAssetPath($Asset, true);
             if (strlen($ThisAsset) && is_readable($ThisAsset) && ($ThisAssetDel = strrpos($ThisAsset, '.')) !== false) {
                 $Success = false;
+                $NoSniff = false;
                 $Type = strtolower(substr($ThisAsset, $ThisAssetDel + 1));
                 if ($Type === 'jpeg') {
                     $Type = 'jpg';
@@ -1601,9 +1602,11 @@ private function eTaggable(string $Asset, ?callable $Callback = null): void
                 } elseif ($Type === 'js') {
                     $MimeType = 'Content-Type: text/javascript';
                     $Success = true;
+                    $NoSniff = true;
                 } elseif ($Type === 'css') {
                     $MimeType = 'Content-Type: text/css';
                     $Success = true;
+                    $NoSniff = true;
                 }
                 if ($Success) {
                     $AssetData = $this->Loader->readFile($ThisAsset);
@@ -1619,6 +1622,9 @@ private function eTaggable(string $Asset, ?callable $Callback = null): void
                         die;
                     }
                     header($MimeType);
+                    if ($NoSniff) {
+                        header('X-Content-Type-Options: nosniff');
+                    }
                     if (is_callable($Callback)) {
                         $AssetData = $Callback($AssetData);
                     }