array or variable loses value when entering if/else statement - php

Question

here is some of the code where I declared the values for $list.
$list['first_name'] = Request::input("first_name");
$list['last_name'] = Request::input("last_name");
when I use dd($list), it shows the value like in my snipped image
but when it enters this if else statement,
if($existing_customer)
{
$customer_id = $existing_customer->customer_id;
}
else
{
dd($list);
$insert_customer["first_name"] = ($list['first_name'] == "undefined" ? "John" : ucfirst($list['first_name']));
$insert_customer["last_name"] = ($list['last_name'] == "undefined" ? "Doe" : ucfirst($list['last_name']));
}
this is the result.
here is the photo of my function, if it could help.
first
second
public function import_submit()
{
$data = Self::get_initial_settings();
/* INITIALIZE AND CAPTURE DATA */
$shop_id = $this->user_info->shop_id;
$sponsor = Tbl_mlm_slot::where("slot_no", Request::input("sponsor"))->where("shop_id", $shop_id)->value("slot_id");
$placement = Tbl_mlm_slot::where("slot_no", Request::input("placement"))->where("shop_id", $shop_id)->value("slot_id");
/* POSITIONING DATA */
$slot_sponsor = $sponsor;
$slot_placement = $placement;
$slot_position = strtolower(Request::input("position"));
/* SLOT GENERATION */
$membership_package_id = Request::input("package_number");
/* JUST ADD TO SLOT IF EXISTING CUSTOMER */
if(Request::input("date_created") == "undefined")
{
$slot_date_created = date("Y-m-d h:i");
}
else
{
$slot_date_created = date("Y-m-d", strtotime(Request::input("date_created")));
}
$existing_customer = Tbl_customer::where("shop_id", $shop_id)->where("email", Request::input("email"))->first();
$list['first_name'] = Request::input("first_name");
$list['last_name'] = Request::input("last_name");
$list['email'] = Request::input("email");
$list['slot_no'] = Request::input("slot_no");
$list['password'] = Request::input("password");
$list['birthday'] = Request::input("birthday");
$list['contact'] = Request::input("contact_number");
$list['gender'] = Request::input("gender");
dd($list); <---- first run of the function, I put one here
if($existing_customer)
{
$customer_id = $existing_customer->customer_id;
}
else
{
dd($list); <--- for the second run of the function, to check what happens to my $list
$insert_customer["shop_id"] = $shop_id;
$insert_customer["first_name"] = ($list['first_name'] == "undefined" ? "John" : ucfirst($list['first_name']));
$insert_customer["last_name"] = ($list['last_name'] == "undefined" ? "Doe" : ucfirst($list['last_name']));
$insert_customer["email"] = ($list['email'] == "undefined" ? "dummy#gmail.com" : $list['email']);
$insert_customer["ismlm"] = 1;
$insert_customer["mlm_username"] = $list['slot_no'];
$insert_customer["password"] = ($list['password'] == "undefined" ? Crypt::encrypt(randomPassword()) : Crypt::encrypt($list['password']));
$insert_customer["created_date"] = $slot_date_created;
$insert_customer["b_day"] = date("Y-m-d", strtotime($list['birthday']));
$insert_customer["birthday"] = date("Y-m-d", strtotime($list['birthday']));
$insert_customer["contact"] = $list['contact'];
$insert_customer["gender"] = strtolower($list['gender']);
$customer_id = Tbl_customer::insertGetId($insert_customer);
/* Insert Customer Address */
$address_purpose[0] = "permanent";
$address_purpose[1] = "billing";
$address_purpose[2] = "shipping";
foreach ($address_purpose as $key => $value)
{
$insert_customer_address["customer_id"] = $customer_id;
$insert_customer_address["country_id"] = 420;
$insert_customer_address["customer_state"] = "";
$insert_customer_address["customer_city"] = "";
$insert_customer_address["customer_zipcode"] = "";
$insert_customer_address["customer_street"] = Request::input("address");
$insert_customer_address["purpose"] = $value;
$insert_customer_address["archived"] = 0;
$insert_customer_address["created_at"] = Carbon::now();
$insert_customer_address["updated_at"] = Carbon::now();
Tbl_customer_address::insert($insert_customer_address);
}
}
}
I can't really see where I went wrong as the values went null just because they entered that if/else statement.