pass a copy when opening dialog

otherwise, any changes the dialog makes will reflect in the calling
view's object

dashboard/src/components/MailboxDialog.vue

@@ -85,6 +85,7 @@ async function onSubmit() {
 
 defineExpose({
   async open(m = null) {
+    m = m ? JSON.parse(JSON.stringify(m)) : null; // make a copy
     busy.value = false;
     formError.value = '';
     mailbox.value = m;
@@ -92,7 +93,7 @@ defineExpose({
     name.value = m ? m.name : '';
     domain.value = m ? m.domain : props.domains[0].domain;
     ownerId.value = m ? m.ownerId : '';
-    aliases.value = m ? JSON.parse(JSON.stringify(m.aliases)) : [];
+    aliases.value = m ? m.aliases : [];
     active.value = m ? m.active : true;
     enablePop3.value = m ? m.enablePop3 : false;
     storageQuotaEnabled.value = m && m.storageQuota ? true : false;