Browser Error: Window function is not a function when called from WebGL JavaScript plugin

Hello,

I am trying to send data from my WebGL player to a JavaScript function declared on the window. However, I keep getting an error:

 Uncaught TypeError: window.relayImgurData is not a function

Here is my JavaScript function placed within my body tag:

   <script type='text/javascript'>
       window.relayImgurData = function(data) {
         console.log(typeof data + ' ' + data);
         console.log(JSON.parse(data));
         addPicture(JSON.parse(data));
       }
   </script>

Here is my jslib file:

     var relay = {
       SendImgurData: function(data) 
       {
           window.relayImgurData(Pointer_stringify(data));
       }
     };
     mergeInto(LibraryManager.library, relay);

And here is the C# script where it is being called:

 using UnityEngine;
 using System.Collections;
 using System.Collections.Generic;
 using System.Linq;
 using System.Runtime.InteropServices;
 
 
 public class ScreenShot : MonoBehaviour {
 
     // the URL (with endpoint) the pic will be sent to
     public string screenShotURL= "https://api.imgur.com/3/image";
 
 
     [DllImport("__Internal")]
     private static extern void SendImgurData(string data);
 
 
     IEnumerator UploadPic(string screenShotURL) {
         // We should only read the screen after all rendering is complete
         yield return new WaitForEndOfFrame();
 
         // Create a texture the size of the screen, RGB24 format
         int width = Screen.width;
         int height = Screen.height;
         var tex = new Texture2D( width, height, TextureFormat.RGB24, false );
 
         // Read screen contents into the texture
         tex.ReadPixels( new Rect(0, 0, width, height), 0, 0 );
         tex.Apply();
 
         // Encode texture into PNG
         byte[] bytes = tex.EncodeToPNG();
         Destroy( tex );
 
         // Add a custom header to request for API authentication
         Dictionary<string, string> headers = new Dictionary<string, string>();
         headers["Authorization"] = "Client-ID xxxxxxxxxxxxxxx";
 
         // Upload to URL specified
         WWW w = new WWW(screenShotURL, bytes, headers);
         yield return w;
         if (!string.IsNullOrEmpty(w.error)) {
             print(w.text);
         }
         else {
             SendImgurData (w.text);
             print("img uploaded =)");
         }
     }
 
     // Initialization for UploadPic
     void UploadPicture(string screenShotURL) {
         StartCoroutine(UploadPic(screenShotURL));
     }
 
     // Takes a screenshot when 'p' is pressed
     void Update() {
         if (Input.GetKeyDown ("p")) {
             UploadPicture(screenShotURL);
             print ("Screenshot =)");
         }
     }
 }

Thank you so much for any help =)