DataTables warning: table id=organizationTable - Invalid JSON response. Laravel

When I successfully update my form from AJax and reload the datatable, I will receive an error message saying DataTables warning: table id=organizationTable - Invalid JSON response. I think the reason is because I returned some data that doesn't match the format of my datatable. Is there a way that I can check the json format of my datatable? So, I can try to create an array that match the format for the updated user and return it as json format. Or I am looking into a wrong direction. Thank you guys.

Controller

public function update(Request $request, $id)
    {
        $user = User::find($id);

        request()->validate([
            'first_name' =>'required',
            'email' => ['required', Rule::unique('users')->ignore($user)],
        ]);

        $user->update($request->all());

        DB::table('model_has_roles')
            ->where('model_id', $user->id)
            ->update(['role_id' => $request->role_id]);

        $request->session()->flash('success', $user->first_name . ' is updated successfully.');

        return response()->json($user);
    }

DataTable View

<table id="organizationTable" class="table table-striped table-bordered">
        <thead>
        <tr>
            <th>Name</th>
            <th>Email</th>
            <th>Role Name</th>
            <th>Status</th>
            <th>Action</th>
        </tr>
        </thead>
        <tbody>
        @foreach($rainman_users as $rainman_user)
            <tr>
                <td style="vertical-align: middle"> </td>
                <td style="vertical-align: middle"></td>
                <td style="vertical-align: middle"></td>
                @if($rainman_user->status_id == 1)
                    <td class="text-success" style="text-align: center; font-style: italic; vertical-align: middle; font-weight: bold;"></td>
                @else
                    <td class="text-danger" style="text-align: center; font-style: italic; vertical-align: middle; font-weight: bold;"></td>
                @endif
                <td style="text-align:center;">
                    <button data-toggle="modal" data-target="#editModal" class="edit-modal btn btn-outline-primary"
                            data-id="" data-first_name=""
                            data-last_name="" data-email=""
                            data-role_id=""
                            data-status_id="">
                            <i class="fa fa-pencil-square-o" aria-hidden="true"></i> Detail
                    </button>
                </td>
            </tr>
        @endforeach
        </tbody>
        <tfoot>
        <tr>
            <th>Name</th>
            <th>Email</th>
            <th>Role Name</th>
            <th>Status</th>
            <th>Action</th>
        </tr>
        </tfoot>
    </table>

JavaScript

$(document).ready(function() {
    $('#organizationTable').DataTable({
    });

    $(document).on('click', '.edit-modal', function() {
        $('.modal-title').text('Edit User');
        $('#id_edit').val($(this).data('id'));
        $('#first_name_edit').val($(this).data('first_name'));
        $('#last_name_edit').val($(this).data('last_name'));
        $('#email_edit').val($(this).data('email'));
        $('#user_role_edit').val($(this).data('role_id'));
        $('#user_status_edit').val($(this).data('status_id'));
        id = $('#id_edit').val();
        $('#editModal').modal('show');
    });

    $('.modal-footer').on('click', '.edit', function() {
        $.ajax({
            type: 'PUT',
            url: '/rainman-users/' + id + '/update',
            data: {
                'id': $("#id_edit").val(),
                'first_name': $("#first_name_edit").val(),
                'last_name': $("#last_name_edit").val(),
                'email': $("#email_edit").val(),
                'role_id': $("#user_role_edit").val(),
                'status_id': $("#user_status_edit").val()
            },
            success: function(data) {
                console.log(data);
                $('#organizationTable').DataTable().ajax.reload();
            }
        });
    });
} );

via Chebli Mohamed