If we analyse the INPUTS, we get:

products_quantity, '0',
products_type, '3',
products_model, '',
products_price, '0',
products_date_available, null,
products_weight, '0',
products_status, '1',
products_virtual, '0',
products_tax_class_id, '0',
manufacturers_id, '0',
products_quantity_order_min, '1',
products_quantity_order_units, '1',
products_priced_by_attribute, '',
product_is_free, '0',
product_is_call, '0',
products_quantity_mixed, '',
product_is_always_free_shipping, '0',
products_qty_box_status, '',
products_quantity_order_max, '',
products_sort_order, '0',
products_discount_type, '0',
products_discount_type_from, '0',
products_price_sorter, '0',
products_image, '',
products_date_added, now(),
master_categories_id, '216'

products_priced_by_attribute, '', Is the first instance of this falling over, because an integer is expected, but no value is given.

It is likely that when this is fixed, the NEXT instance of an expected integer value which is empty is:
products_quantity_mixed, '', (INTEGER IS EXPECTED)

... and then:
products_qty_box_status, '', (INTEGER IS EXPECTED)

...whereas:
products_image, '', (This field is VARCHAR, so being empty does not matter).

So... MAYBE if you add the three expected integers via Dr Byte's suggested fix...

Code:
// Data-cleaning to prevent MySQL5 data-type mismatch errors:
    $tmp_value = zen_db_prepare_input($_POST['products_quantity']);
    $products_quantity = (!zen_not_null($tmp_value) || $tmp_value=='' || $tmp_value == 0) ? 0 : $tmp_value;
    $tmp_value = zen_db_prepare_input($_POST['products_price']);
    $products_price = (!zen_not_null($tmp_value) || $tmp_value=='' || $tmp_value == 0) ? 0 : $tmp_value;
    $tmp_value = zen_db_prepare_input($_POST['products_weight']);
    $products_weight = (!zen_not_null($tmp_value) || $tmp_value=='' || $tmp_value == 0) ? 0 : $tmp_value;
    $tmp_value = zen_db_prepare_input($_POST['manufacturers_id']);
    $manufacturers_id = (!zen_not_null($tmp_value) || $tmp_value=='' || $tmp_value == 0) ? 0 : $tmp_value;
    $tmp_value = zen_db_prepare_input($_POST['products_priced_by_attribute']);
    $products_priced_by_attribute = (!zen_not_null($tmp_value) || $tmp_value=='' || $tmp_value == 0) ? 0 : $tmp_value;
    $tmp_value = zen_db_prepare_input($_POST['products_quantity_mixed']);
    $products_quantity_mixed = (!zen_not_null($tmp_value) || $tmp_value=='' || $tmp_value == 0) ? 0 : $tmp_value;
    $tmp_value = zen_db_prepare_input($_POST['products_qty_box_status']);
    $products_qty_box_status = (!zen_not_null($tmp_value) || $tmp_value=='' || $tmp_value == 0) ? 0 : $tmp_value;

    $sql_data_array = array('products_quantity' => $products_quantity,
                            'products_type' => zen_db_prepare_input($_GET['product_type']),
                            'products_model' => zen_db_prepare_input($_POST['products_model']),
                            'products_price' => $products_price,
                            'products_date_available' => $products_date_available,
                            'products_weight' => $products_weight,
                            'products_status' => zen_db_prepare_input((int)$_POST['products_status']),
                            'products_virtual' => zen_db_prepare_input((int)$_POST['products_virtual']),
                            'products_tax_class_id' => zen_db_prepare_input((int)$_POST['products_tax_class_id']),
                            'manufacturers_id' => $manufacturers_id,
                            'products_quantity_order_min' => zen_db_prepare_input($_POST['products_quantity_order_min']),
                            'products_quantity_order_units' => zen_db_prepare_input($_POST['products_quantity_order_units']),
                            'products_priced_by_attribute' => zen_db_prepare_input($_POST['products_priced_by_attribute']),
                            'product_is_free' => zen_db_prepare_input((int)$_POST['product_is_free']),
                            'product_is_call' => zen_db_prepare_input((int)$_POST['product_is_call']),
                            'products_quantity_mixed' => zen_db_prepare_input($_POST['products_quantity_mixed']),
                            'product_is_always_free_shipping' => zen_db_prepare_input((int)$_POST['product_is_always_free_shipping']),
                            'products_qty_box_status' => zen_db_prepare_input($_POST['products_qty_box_status']),
                            'products_quantity_order_max' => zen_db_prepare_input($_POST['products_quantity_order_max']),
                            'products_sort_order' => (int)zen_db_prepare_input($_POST['products_sort_order']),
                            'products_discount_type' => zen_db_prepare_input($_POST['products_discount_type']),
                            'products_discount_type_from' => zen_db_prepare_input($_POST['products_discount_type_from']),
                            'products_price_sorter' => zen_db_prepare_input($_POST['products_price_sorter'])
                            );