Blank page with just the logo

I finally got Piwik to display something, and all I get is the logo.

Here is the generated HTML. What’s crashing? If it’s a PHP error, why does it not display it?

<!DOCTYPE html>
<html id="ng-app" ng-app="piwikApp">
    <meta charset="utf-8">
    <meta name="robots" content="noindex,nofollow">
    <title>Piwik 3.0.1 &rsaquo; Installation</title>
    <link rel="stylesheet" type="text/css" href="index.php?module=Installation&action=getInstallationCss"/>
    <script type="text/javascript" src="index.php?module=Installation&action=getInstallationJs"></script>
    <link rel="shortcut icon" href="plugins/CoreHome/images/favicon.png"/>
<body ng-app="app" id="installation">

<div class="container">
    <div class="header">
        <div class="logo">
            <img title="Piwik 3.0.1 - free&#x2F;libre&#x20;analytics&#x20;platform" src="plugins/Morpheus/images/logo.png"/>
            <p>free/libre analytics platform</p>
        <div class="language-selector">

The server log shows:

SoftException in Application.cpp:632: Directory “/home/elithi5/public_html/analytics” is writeable by group

I did try to delete all files in /tmp/. No change

I hired a consultant, who fixed it. He said that the problem is that PHP did not have enough memory, and that it was really tough to find the problem, because the PHP error was logged in a log that was buried somewhere in the VPS (virtual Private Server).