“Failed to load resource: the server responded with a status of 404 (Not Found)”

I get this error message when trying to load in a JS-file in Ionic.

I made sure that the path is correct but I still end up with this response.

Error-Msg

My Index.html:

<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="utf-8"/>
  <title>Ionic App</title>
  <base href="/"/>
  <meta name="color-scheme" content="light dark"/>
  <meta name="viewport" content="viewport-fit=cover, width=device-width, initial-scale=1.0, minimum-scale=1.0, maximum-scale=1.0, user-scalable=no"/>
  <meta name="format-detection" content="telephone=no"/>
  <meta name="msapplication-tap-highlight" content="no"/>
  <script type="text/javascript" src="galerie.js"></script> <!---------------------JS-file->

  <link rel="icon" type="image/png" href="assets/icon/favicon.png"/>

  <!-- add to homescreen for ios -->
  <meta name="apple-mobile-web-app-capable" content="yes"/>
  <meta name="apple-mobile-web-app-status-bar-style" content="black"/>
  <link rel="manifest" href="manifest.webmanifest">
  <meta name="theme-color" content="#1976d2">
  <link rel="manifest" href="manifest.webmanifest">
  <meta name="theme-color" content="#1976d2">
  <link rel="manifest" href="manifest.webmanifest">
  <meta name="theme-color" content="#1976d2">
</head>

<body>
  <app-root></app-root>
  <noscript>Please enable JavaScript to continue using this application.</noscript>
</body>
</html>

I’m still new to Ionic, so I don’t really know where the problem could lie.