I received this error when trying to uninstall Snapshot Pro on my client's website.
The website, which is an attorney site, became "Internal Server Error" and the site was not accessible. I deleted the htaccess file, but then had to go one-by-one through plugins to determine the issue. Snapshot was the last one installed, and I had to manually delete it via FTP.
This was the error:
Fatal error: Call to private WPMUDEVSnapshot::__construct() from invalid context in /home/bagoliefriedman/public_html/wp-content/plugins/snapshot/uninstall.php on line 7