Error – Class name must be a valid object or a string

Get this error recurring on several installs, otherwise a fantastic plugin.
[07-Dec-2016 03:35:10 UTC] PHP Fatal error: Class name must be a valid object or a string in /wp-content/plugins/rs-head-cleaner/rs-head-cleaner.php on line 799
(updated to latest ver.)
[07-Dec-2016 09:04:46 UTC] PHP Fatal error: Class name must be a valid object or a string in /wp-content/plugins/rs-head-cleaner/rs-head-cleaner.php on line 820
——
// Generated by the RS System Diagnostic Plugin //

//// Browser of Current Viewer ///////////////////

Platform: Windows
Browser Name: Chrome
Browser Version: 54.0.2840.99
User Agent String: Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/54.0.2840.99 Safari/537.36

//// End Browser of Current Viewer ///////////////

Website Name:

WordPress Address (URL): http://www. | site_url() – The location where your WordPress core files reside.
Site Address (URL): http://www. | home_url() – The URL people should use to get to your site.

WordPress Version: 4.7
Multisite: No
Permalink Structure: /%postname%
Active Theme: Estate Premium 2.2

Web Host: Not Detected
Name Servers: ns1.hostmonster.com | ns2.hostmonster.com

PHP Version: 5.6.27
MySQL Version: 5.6.32-78.1-log
Server Software: Apache / Linux
Server Hostname: .hostmonster.com

WP Memory Limit: 40M | WARNING – PERFORMANCE: WordPress Memory Limit too low. Should be at least 64MB. 96-128MB+ is recommended.
WP Admin Memory Limit: 256M
Current WP Memory Used: 39.75M
Max WP Memory Used: 39.75M
PHP Safe Mode: No
PHP Memory Limit: 256M
PHP Upload Max Size: 64M
PHP Post Max Size: 64M
PHP Upload Max Filesize: 64M
PHP Time Limit: 30
PHP Max Input Vars: 1000
PHP Arg Separator: &
PHP Allow URL File Open: Yes
PHP Short Open Tags: Enabled | WARNING – SECURITY: 'short_open_tag' should be disabled.
Expose PHP: No

WP_DEBUG: Disabled
WP_DEBUG_LOG: Disabled
WP_DEBUG_DISPLAY: Enabled
SCRIPT_DEBUG: Disabled
WP_CACHE: Disabled
AUTOSAVE_INTERVAL: 60
WP_POST_REVISIONS: 1
EMPTY_TRASH_DAYS: 30
DISALLOW_FILE_EDIT: Not set | WARNING – SECURITY: This should be enabled.

WP Database Size: 6.67M
WP Table Prefix Length: 3 | ERROR: Too Short
WP Table Prefix Default: Yes | WARNING – SECURITY: The WP Table Prefix should be changed to a custom value between 8-16 characters long.

Show On Front: page
Page On Front: Home (#821)
Page For Posts: (#0)
Registered Post Stati: publish, future, draft, pending, private, trash, auto-draft, inherit

WP Remote Post: wp_remote_post() works

PHP Sessions: Inactive
Default Session Name: PHPSESSID | WARNING – SECURITY: 'session.name' should be set to a custom value, not the PHP default.
Session Cookie Path: /
Session Save Path: /tmp
Use Session Cookies: On
Session Use Cookies Only: On
Session Cookie HTTP Only: Off | WARNING – SECURITY: 'session.cookie_httponly' should be enabled to prevent JavaScript from accessing Session Cookies.
Session Cookie HTTP Only: Off | WARNING – SECURITY: 'session.cookie_httponly' should be enabled to prevent JavaScript from accessing Session Cookies.

DISPLAY ERRORS: N/A
ERROR LOGGING: On
ERROR LOG LOCATION: error_log
ERROR REPORTING LEVEL: E_RECOVERABLE_ERROR | E_USER_WARNING | E_USER_ERROR | E_COMPILE_ERROR | E_CORE_WARNING | E_CORE_ERROR | E_PARSE | E_WARNING | E_ERROR

FSOCKOPEN: Your server supports fsockopen.
cURL: Your server supports cURL.
SOAP Client: Your server has the SOAP Client enabled.
SUHOSIN: Your server does not have SUHOSIN installed.
MySQLi: Your server has the MySQLi extension enabled.

ACTIVE PLUGINS:

Add Headers: 2.0.1
Anti-Malware Security and Brute-Force Firewall: 4.16.39
Estate Plus: 1.0
Favicon by RealFaviconGenerator: 1.3.9
Google XML Sitemaps: 4.0.8
Meta Slider: 3.3.7
RS Head Cleaner Plus: 1.4.3.4
RS System Diagnostic: 1.0.3
TinyMCE Advanced: 4.4.3
Wordfence Security: 6.2.7

TOTAL ACTIVE PLUGINS: 10

INACTIVE PLUGINS:

Bulk Resize Media: 1.1
Optimize Database after Deleting Revisions: 4.2.1
Page Builder by SiteOrigin: 2.4.20
SiteOrigin CSS: 1.1.2
SiteOrigin Masonry: 1.0.3

TOTAL INACTIVE PLUGINS: 5