CheckStatistics#assembleBody(): avoid divisions by 0

A too small check interval can let the last and next check appear to be at
the same time due to rounding to milliseconds. Their difference is 0 which
shall not be used for division.

library/Icingadb/Widget/Detail/CheckStatistics.php

@@ -122,6 +122,8 @@ protected function assembleBody(BaseHtmlElement $body)
             // The only way to detect this, is to measure how old the last update is.
             $nextCheckTime = null;
             $leftNow = 0;
+        } elseif ($nextCheckTime - $lastUpdateTime <= 0) {
+            $leftNow = 0;
         } else {
             $leftNow = 100 * (1 - ($nextCheckTime - time()) / ($nextCheckTime - $lastUpdateTime));
             if ($leftNow > 100) {
@@ -133,7 +135,7 @@ protected function assembleBody(BaseHtmlElement $body)
 
         $styleElement->addFor($progressBar, ['width' => sprintf('%F%%', $leftNow)]);
 
-        $leftExecutionEnd = $nextCheckTime !== null ? $durationScale * (
+        $leftExecutionEnd = $nextCheckTime !== null && $nextCheckTime - $lastUpdateTime > 0 ? $durationScale * (
             1 - ($nextCheckTime - $executionEndTime) / ($nextCheckTime - $lastUpdateTime)
         ) : 0;