fix(frontend/backend): suppress php warnings for the combined message…

… list view and correct the search event triggered on the search input for each mailbox (#1418)

modules/imap/functions.php

@@ -1644,13 +1644,13 @@ function flattenMessagesLists($messagesLists, $listSize) {
                 $part = array_slice($list, 0, $listSize);
                 $endList = array_merge($endList, $part);
                 $messagesLists[$index] = array_slice($list, $listSize);
-                $sizesTaken[$index] = $sizesTaken[$index] ? $sizesTaken[$index] + count($part) : count($part);
+                $sizesTaken[$index] = isset($sizesTaken[$index]) ? $sizesTaken[$index] + count($part) : count($part);
                 $totalTakens = array_sum(array_values($sizesTaken));
                 if ($totalTakens > $max) {
                     $sizesTaken[$index] = $sizesTaken[$index] - ($totalTakens - $max);
                 }
             } else {
-                $sizesTaken[$index] = $sizesTaken[$index] ? $sizesTaken[$index] : 0;
+                $sizesTaken[$index] = isset($sizesTaken[$index]) ? $sizesTaken[$index] : 0;
             }
         }
     }

modules/imap/site.js

@@ -437,11 +437,16 @@ var setup_imap_folder_page = async function(listPath, listPage = 1) {
             select_imap_folder(listPath, listPage, true);
         }
     });
-    $('.imap_filter').on("change", function() { $('#imap_filter_form').trigger('submit'); });
-    $('.imap_sort').on("change", function() {
+    $('.imap_filter').on("change", function(e) { 
+        e.preventDefault();
         $('#imap_filter_form').trigger('submit');
     });
-    $('.imap_keyword').on('search', function() {
+    $('.imap_sort').on("change", function(e) {
+        e.preventDefault();
+        $('#imap_filter_form').trigger('submit');
+    });
+    $('.imap_keyword').on('search', function(e) {
+        e.preventDefault();
         $('#imap_filter_form').trigger('submit');
     });