Compatiblity changes for Boost under PHP 8.1 (#5338)

Closes #5338

CHANGELOG

@@ -2,7 +2,7 @@ Cacti CHANGELOG
 
 1.2.25
 -SECURITY#5318: Multiple minor stored XSS vulnerabilities in Cacti 1.2.24
--issue#2959: Multi-threaded cli/rebuild_poller_cache.php, deprecated push_out_hosts.php 
+-issue#2959: Multi-threaded cli/rebuild_poller_cache.php, deprecated push_out_hosts.php
 -issue#5254: Created a data source template to specify the snmp port, but it doesn't seem to work properly
 -issue#5255: Data query xml path with space problem
 -issue#5258: Warnings occur when installing thold plugin and as such thold will not upgrade correctly
@@ -22,6 +22,7 @@ Cacti CHANGELOG
 -issue#5317: Data Source Info Mode produces invalid recommendations
 -issue#5319: Data Source Debug 'Run All' generates too many log messages
 -issue#5323: Cosmetic error in the system utilities - rebuild poller cache - description
+-issue#5338:
 -feature: Upgrade billboard.js to version 3.7.4
 -feature: Upgrade d3.js to version 7.8.2
 

poller_boost.php

@@ -119,14 +119,14 @@
 	/* find out if it's time to collect device information
 	 * support both old and new formats.
 	 */
-	$boost_last_run_time = read_config_option('boost_last_run_time');
+	$boost_last_run_time = read_config_option('boost_last_run_time') ?? '';
 	if (!is_numeric($boost_last_run_time)) {
 		$last_run_time = strtotime($boost_last_run_time);
 	} else {
 		$last_run_time = $boost_last_run_time;
 	}
 
-	$boost_next_run_time = read_config_option('boost_next_run_time');
+	$boost_next_run_time = read_config_option('boost_next_run_time') ?? '';
 	if (!is_numeric($boost_next_run_time)) {
 		$next_run_time = strtotime($boost_next_run_time);
 	} else {
@@ -308,6 +308,9 @@ function boost_prepare_process_table() {
 	boost_debug('Parallel Process Setup Begins.');
 
 	$boost_poller_status = read_config_option('boost_poller_status');
+	if (!$boost_poller_status) [
+		$boost_poller_status = 'not started';
+	]
 
 	/* detect a process that has overrun it's warning time */
 	if (substr_count($boost_poller_status, 'running')) {