PHP page stops loading halfway through - Doesn't finish code - php

Question

I have a web application where I look through all mails in the inbox of my Gmail-account and search for specific strings to pick out different emails.
On this app I can set a limit on how many emails to search. If I set this limit to "200" or lower it works just fine most of the times.
But if i increase the limit to 400 and up that, 99% of the times, the application/page stops loading. And the code doesn't finish.
I have enabled so PHP shows error messages via the host website and also via this code at the begining of each php page:
<?php
error_reporting(E_ALL);
ini_set('display_errors', '1');
?>
However, when the page stops loading, no error messages is displayed. (And it does display on other errors)
This is the code I'm using, together with Gmail API.
<?php
//Authentication with Gmail API happens here
$gmail = new Google_Service_Gmail($client);
$number_of_emails_to_fetch = 500;
$list = $gmail->users_messages->listUsersMessages('me', ['maxResults' => $number_of_emails_to_fetch]);
$filename = "unsubscribe-show-all.php";
$sql_table_name = create_table();
$connection = open_connection();
while ($list->getMessages() != null) {
foreach ($list->getMessages() as $mlist) {
$message_id = $mlist->id;
$optParamsGet2['format'] = 'full';
$single_message = $gmail->users_messages->get('me', $message_id, $optParamsGet2);
$payload = $single_message->getPayload();
$parts = $payload->getParts();
// With no attachment, the payload might be directly in the body, encoded.
$body = $payload->getBody();
$FOUND_BODY = FALSE;
// If we didn't find a body, let's look for the parts
if(!$FOUND_BODY) {
foreach ($parts as $part) {
if($part['parts'] && !$FOUND_BODY) {
foreach ($part['parts'] as $p) {
if($p['parts'] && count($p['parts']) > 0){
foreach ($p['parts'] as $y) {
if(($y['mimeType'] === 'text/html') && $y['body']) {
$FOUND_BODY = decodeBody($y['body']->data);
break;
}
}
} else if(($p['mimeType'] === 'text/html') && $p['body']) {
$FOUND_BODY = decodeBody($p['body']->data);
break;
}
}
}
if($FOUND_BODY) {
break;
}
}
}
// If we didn't find the body in the last parts,
// let's loop for the first parts (text-html only)
if(!$FOUND_BODY) {
foreach ($parts as $part) {
if($part['body'] && $part['mimeType'] === 'text/html') {
$FOUND_BODY = decodeBody($part['body']->data);
break;
}
}
}
// With no attachment, the payload might be directly in the body, encoded.
if(!$FOUND_BODY) {
$FOUND_BODY = decodeBody($body['data']);
}
if(!$FOUND_BODY) {
$FOUND_BODY = '(No message)';
}
}
?>
After this code I have more code that handles inserting different links into databases followed by a redirection.
However, i tried removing that code and only running the code above + the redirection, but the page still stops loading, so I figure it has something to do with this snippet.
Any advice on where to read, or hints on how to fix this would be greatly appreciated!