Fix duplicate dashlets (#5245)

fixes #5203

Author: nilmerg

library/Icinga/File/Ini/IniWriter.php

@@ -69,7 +69,7 @@ public function __construct(Config $config, $filename, $filemode = 0660, $option
      */
     public function render()
     {
-        if (file_exists($this->filename)) {
+        if ($this->filename !== null && file_exists($this->filename)) {
             $oldconfig = Config::fromIni($this->filename);
             $content = trim(file_get_contents($this->filename));
         } else {

library/Icinga/Web/Widget/Dashboard.php

@@ -147,15 +147,17 @@ protected function loadUserDashboardsFromFile($file, Navigation $dashboardNaviga
                 if ($dashboardPane !== null) {
                     $key = $dashboardPane->getLabel();
                 }
+                $pane = null;
                 if ($this->hasPane($key)) {
-                    $panes[$key] = $this->getPane($key);
+                    $pane = $this->getPane($key);
                 } else {
-                    $panes[$key] = new Pane($key);
+                    $pane = new Pane($key);
+                    $panes[$key] = $pane;
                     $panes[$key]->setTitle($part->title);
                 }
-                $panes[$key]->setUserWidget();
+                $pane->setUserWidget();
                 if ((bool) $part->get('disabled', false) === true) {
-                    $panes[$key]->setDisabled();
+                    $pane->setDisabled();
                 }
             } else {
                 list($paneName, $dashletName) = explode('.', $key, 2);