javascript file not able to be requested from html but other type such as css, images were fetched successfully

I have some questions about why my js files (there are two here in this html) not able to be fetched from my localhost when I am testing in Firefox (for both of them, I got the NS_ERROR_NET_RESET error when I check the FireFox Developer Network Tab). Other files such as .css, .png were able to be transferred when I entered https://localhost:8080 into my tab.

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

<head>
    <!-- <base href="index.html"> -->
    
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <link href="myCustomStyle.css" rel="stylesheet" type="text/css">
    <link rel="icon" type="image/png" href="myFavoriteicon.png">
        
     <!-- This is the first script tag to request a .js file -->
    <script src="/tools.js" async> </script>
    <title>Document's Special Title here!lala</title>
    
</head>
<body>
    This is HTML here!
    

    <p class="hometown">
        Another line here!
    </p>

    <img src="/check.png" alt="an image here" width="100" height="88">

    <p id="para1">
        Should be in Yellow color this line.
        Document.get
    </p>

    <p>
        <a href="https://www.Youtube.com/">
            <img src="https://www.tutorialspoint.com/assets/questions/media/426142-1668760872.png" alt="not shown!" style="width:50px;height:50px;">
        </a>
    </p>

    <h1 style ="color:blue"> A simple Chat Application</h1>
    <h2> a h2 here </h2>
    <p> a new paragraph!</p>
    <p> current module: __dirname</p>

    
    <label for="ChatBox1" id="ChatboxCol"> Conversation (You send): </label>
    <input type="text" id="ChatBox1"
    name = "Name" required minlength="8"
    maxlength="24" size="33" /> 

    
    
    <script>
        document.addEventListener("load", () => {
          console.log("This function is executed once the page is fully loaded");
        });
    </script>
    
    <!-- This is the second script tag to request a .js file -->
    <script src="./ListOfEventListenersUsed.js" type="text/javascript" async> </script> 
    
    </body>
</html>

And this is my firefox network tool tab:

enter image description here

could someone advises what I should do? thanks

I have tried testing in chrome as well, same thing happens. None of my .js file were fetched successfully. The NS_ERROR_NET_RESET appears for those two .js files.