EntryPointNotFoundException in Unity

[Dreitser]

This library is amazing, Sending to Unity is perfect. When trying to send back to React, the setup we used from the readmeis causing this error in Unity:

EntryPointNotFoundException: ConnectedToWeb
GameController.SendConnectedToWeb () (at Assets/GameController.cs:19)
GameController.ConnectUnity () (at Assets/GameController.cs:24)
UnityEngine.Events.InvokableCall.Invoke () (at /Users/bokken/buildslave/unity/build/Runtime/Export/UnityEvent/UnityEvent.cs:166)
UnityEngine.Events.UnityEvent.Invoke () (at /Users/bokken/buildslave/unity/build/Runtime/Export/UnityEvent/UnityEvent/UnityEvent_0.cs:58)
UnityEngine.UI.Button.Press () (at Library/PackageCache/[email protected]/Runtime/UI/Core/Button.cs:68)
UnityEngine.UI.Button.OnPointerClick (UnityEngine.EventSystems.PointerEventData eventData) (at Library/PackageCache/[email protected]/Runtime/UI/Core/Button.cs:110)
UnityEngine.EventSystems.ExecuteEvents.Execute (UnityEngine.EventSystems.IPointerClickHandler handler, UnityEngine.EventSystems.BaseEventData eventData) (at Library/PackageCache/[email protected]/Runtime/EventSystem/ExecuteEvents.cs:50)
UnityEngine.EventSystems.ExecuteEvents.Execute[T] (UnityEngine.GameObject target, UnityEngine.EventSystems.BaseEventData eventData, UnityEngine.EventSystems.ExecuteEvents+EventFunction`1[T1] functor) (at Library/PackageCache/[email protected]/Runtime/EventSystem/ExecuteEvents.cs:261)
UnityEngine.EventSystems.EventSystem:Update() (at Library/PackageCache/[email protected]/Runtime/EventSystem/EventSystem.cs:377)

Using Unity ver 2019.4.29f1 LTS and ver 7 of react-unity-webgl
Here is the code we're running:
GameController.cs:

// GameController.cs
using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using UnityEngine.UI;
using System.Runtime.InteropServices;
public class GameController : MonoBehaviour
{
    public GameObject connectBtn;
    public GameObject connectedImg;
    public GameObject receivedConnectedImg;
    [DllImport("__Internal")]
    private static extern void ConnectedToWeb ();
    void Start()
    {
       receivedConnectedImg.SetActive(false);
       connectedImg.SetActive(false);
    }
    public void SendConnectedToWeb () {
       ConnectedToWeb ();
        connectedImg.SetActive(true);
    }
    public void ConnectUnity(){
        receivedConnectedImg.SetActive(true);
        SendConnectedToWeb();
    }
}

MyPluging.jslib:

// Plugins/WebGL/MyPlugin.jslib
mergeInto(LibraryManager.library, {
  // Create a new function with the same name as
  // the event listeners name and make sure the
  // parameters match as well.

  ConnectedToWeb: function () {
    // Within the function we're going to trigger
    // the event within the ReactUnityWebGL object
    // which is exposed by the library to the window.

    ReactUnityWebGL.ConnectedToWeb();
  },
});

[Dreitser]

This from Unity helped me resolve the issue. Now it works like a charm.
https://docs.unity3d.com/Manual/webgl-interactingwithbrowserscripting.html