new content element CE; php8 compatibility issues

app/modules/contenttype.php

         $this->href= $f3->get('SITE_URL').str_replace($f3->get('CONTENT'),"",$this->config['path']);
 
         foreach ($this->keys as $k=>$v) {
-            $this->values[$v] = $keys[$k];
+            if (array_key_exists($k, $keys)) {
+                $this->values[$v] = $keys[$k];
+            } else {
+                $this->values[$v] = '';
+            }
         }
 
         $ke = explode("/",$this->config['path']);

app/modules/filesinfolders.php

                 }
                 break;
             
+            case 'CE':
+                switch($request[1]) {
+                case 'publication':
+                    $CE = new \Modules\CPublication($this->config,['path'=>$this->folder]);
+                    if(count($request)>2) {
+                        $CE->set_layout($request[2]);
+                    }
+                    $new = $CE;
+                    break;
+                }
+                break;
+            
             case 'TOC':
                 // throw away TOC part of request, we don't need it
                 array_shift($request); 
                 $toc = new \Modules\TOC($request,$this->folder,$body);
                 $toc->dispatch();
+                
                 $new=sprintf("<div class=\"TOC %s\">%s</div>",
                              array_shift($request),
                              $toc);

app/modules/toc.php

         case 'concerts':
             $this->load('\Modules\CConcert');
             break;
+        case 'publication':
+        case 'publications':
+            $this->load('\Modules\CPublication');
+            break;
         }
     }
 
     function apply_filters() {
         foreach($this->elements as $k=>$v) {
             $show = true;
-            if (count($this->filters['must_have'])) {
+            if (array_key_exists('must_have', $this->filters) && count($this->filters['must_have'])) {
                 $show = false;
                 foreach ($this->filters['must_have'] as $l=>$w) {
                     $ke = array_keys($w);
                     }
                 }
             }
-            if (count($this->filters['must_not_have'])) {
+            if (array_key_exists('must_not_have', $this->filters) && count($this->filters['must_not_have'])) {
                 foreach ($this->filters['must_not_have'] as $l=>$w) {
                     $ke = array_keys($w);
                     $key = $ke[0];

app/views/header2.htm

     </div>  
   </check>
   
-  <check if="{{ @logo }}">
+  <check if="{{ isset(@logo) }}">
     <true>
       <a href="{{ @SITE_URL }}/"><h1>
           <img src="/{{ @logo }}" alt="{{ @title }}" />