ZP-947 Log warning only if the folder is not found.

Released under the Affero GNU General Public License (AGPL) version 3.

src/backend/kopano/exporter.php

@@ -94,8 +94,10 @@ class ExportChangesICS implements IExportChanges{
             $folder = false;
             if ($entryid) {
                 $folder = mapi_msgstore_openentry($this->store, $entryid);
+                if (!$folder) {
                     ZLog::Write(LOGLEVEL_WARN, sprintf("ExportChangesICS(): Error, mapi_msgstore_openentry() failed: 0x%08X", mapi_last_hresult()));
                 }
+            }
 
             // Get the actual ICS exporter
             if($folderid) {