I have created a DataTables Editor using the generator and attempted to create a record via the editor and have received an error "A system error has occurred".

Here is the Firefox error data:

The frequency.php code:

<?php

/*
 * Editor server script for DB table frequency
 * Created by http://editor.datatables.net/generator
 */

// DataTables PHP library and database connection
include( "lib/DataTables.php" );

// Alias Editor classes so they are easy to use
use
    DataTables\Editor,
    DataTables\Editor\Field,
    DataTables\Editor\Format,
    DataTables\Editor\Mjoin,
    DataTables\Editor\Options,
    DataTables\Editor\Upload,
    DataTables\Editor\Validate,
    DataTables\Editor\ValidateOptions;

// Build our Editor instance and process the data coming from _POST
Editor::inst( $db, 'frequency', 'frequency.frequencyid' )
    ->fields(
        Field::inst( 'frequency.organisationid' )
            ->options( 'organisation','organisationid', 'orgname')
            ->validator( 'Validate::dbValues' ),
        Field::inst( 'organisation.orgname' ),
        Field::inst( 'organisation.inactive'),
        Field::inst( 'frequency.fdescription' )
            ->validator( Validate::notEmpty( ValidateOptions::inst()
                ->message('A Description is required') ) )
            ->validator( Validate::minMaxLen( 1, 50 ) ),
        Field::inst( 'frequency.offsetindays' )
            ->validator( Validate::notEmpty( ValidateOptions::inst()
                ->message('Offset in days is required') ) )
            ->validator( Validate::minNum( 1, ValidateOptions::inst()
                ->message( 'Offset In days greater than 0' ) ) ),
        Field::inst( 'frequency.isdeleted' )
            ->setFormatter(function ($val, $data, $opts) {
                return ! $val ? 0 : 1;          
            })
    )
    ->leftJoin( 'organisation', 'organisation.organisationid', '=', 'frequency.organisationid')
    ->process( $_POST )
    ->json();
?>

Here is the frequency.js

/*
 * Editor client script for DB table frequency
 * Created by http://editor.datatables.net/generator
 */

(function($){

$(document).ready(function() {
    var editor = new $.fn.dataTable.Editor( {
        ajax: 'php/table.frequency.php',
        table: '#frequency',
        fields: [
            {
                "label": "Organisation:",
                "name": "frequency.organisationid",
                "type": "select"
            },
            {
                "label": "Description:",
                "name": "frequency.fdescription"
            },
            {
                "label": "Offset In days:",
                "name": "frequency.offsetindays"
            },
            {
                "label": "Is Deleted:",
                "name": "frequency.isdeleted",
                "type": "checkbox",
                "separator": "|",
                "options": [
                    {label: '', value: 1}
                ]
            }
        ]
    } );

    var table = $('#frequency').DataTable( {
        ajax: 'php/table.frequency.php',
        columns: [
            { 
                "data": "organisation.orgname",
                "render": function (data, type, row){
                    if (row.organisation.inactive == 0){
                        return data + '(Inactive)';
                    }
                    else{
                        return data;
                    }
                }
            },
            {
                "data": "frequency.fdescription"
            },
            {
                "data": "frequency.offsetindays"
            },
            {
                "data": "frequency.isdeleted",
                "render": function (data, type, row){
                    if (type === 'display'){
                        return '<input type="checkbox" class="editor-active">';                 
                    }
                    return data;                
                },
                "className": "dt-body-center"
            }
        ],
        select: true,
        lengthChange: false,
        responsive: true,
        rowCallback: function (row, data) {
         // Set the checked state of the checkbox in the table
         $('input.editor-active', row).prop('checked', data.isdeleted ==1);
      }
    } );

    new $.fn.dataTable.Buttons( table, [
        { extend: "create", editor: editor },
        { extend: "edit",   editor: editor },
        { extend: "remove", editor: editor }
    ] );

    table.buttons().container()
        .appendTo( $('.col-md-6:eq(0)', table.table().container() ) );
} );

    $('#frequency').on( 'change', 'input.editor-active', function () {
        editor
            .edit( $(this).closest('tr'), false )
            .set( 'frequency.isdeleted', $(this).prop( 'checked' ) ? 1 : 0 )
            .submit();
    } );
    
   $('#frequency').on( 'init.dt', function(e, settings, json) {
    var select = editor.field( 'frequency.organisationid').input();
    var jData = json.data;
    var OrgIsAvail = 0;
    var disabledOrgs = [];
    var OrgObj = {};
    for(i = 0; i < jData.length; i++){
        OrgID = jData[i]['frequency'].organisationid;
        OrgIsAvail = jData[i]['organisation'].inactive;
        if (OrgIsAvail == 1){
            // put the number in the object (as a key)
                OrgObj[OrgID] = true;               
        }
    }

        // copy numbers out of object into array
        for (var l in OrgObj){
            if (OrgObj.hasOwnProperty(l)){
                disabledOrgs.push(l);       
            }       
        }       
    var orgOpt = '';
    for(j = 0; j < select[0].length; j++){
        orgOpt = select[0][j];
        for (k = 0; k < disabledOrgs.length; k++){
                if (orgOpt.value == disabledOrgs[k]){
                    orgOpt.setAttribute('disabled','disabled');
                    break;
                }           
        }
    }
   });
}(jQuery));

And here is the frequency.html:

<!doctype html>
<html>
    <head>
        <meta http-equiv="content-type" content="text/html; charset=utf-8" />
        
        <title>DataTables Editor - frequency</title>

        <link rel="stylesheet" type="text/css" href="https://cdn.datatables.net/v/bs4-4.1.1/jq-3.3.1/moment-2.18.1/dt-1.10.18/b-1.5.6/b-flash-1.5.6/b-print-1.5.6/fh-3.1.4/r-2.2.2/sl-1.3.0/datatables.min.css">
        <link rel="stylesheet" type="text/css" href="css/generator-base.css">
        <link rel="stylesheet" type="text/css" href="css/editor.bootstrap4.min.css">

        <script src="https://cdnjs.cloudflare.com/ajax/libs/popper.js/1.11.0/umd/popper.min.js"></script>
        <script type="text/javascript" charset="utf-8" src="https://cdn.datatables.net/v/bs4-4.1.1/jq-3.3.1/moment-2.18.1/dt-1.10.18/b-1.5.6/b-flash-1.5.6/b-print-1.5.6/fh-3.1.4/r-2.2.2/sl-1.3.0/datatables.min.js"></script>
        <script type="text/javascript" charset="utf-8" src="js/dataTables.editor.min.js"></script>
        <script type="text/javascript" charset="utf-8" src="js/editor.bootstrap4.min.js"></script>
        <script type="text/javascript" charset="utf-8" src="js/table.frequency.js"></script>
    </head>
    <body class="bootstrap4">
        <div class="container">

            <h1>
                DataTables Editor <span>frequency</span>
            </h1>
            
            <table cellpadding="0" cellspacing="0" border="0" class="table table-striped table-bordered" id="frequency" width="100%">
                <thead>
                    <tr>
                        <th>Organisation</th>
                        <th>Description</th>
                        <th>Offset In Days</th>
                        <th>Is Deleted</th>
                    </tr>
                </thead>
            </table>

        </div>
    </body>
</html>

Here is the MySQL table code:

Hoping that someone could point out my error.

Thanks in advance