Fixed #2853 - Overlay components don't work with SSR

src/components/portal/Portal.vue

@@ -2,9 +2,11 @@
     <template v-if="inline">
         <slot></slot>
     </template>
-    <Teleport v-else-if="isClient" :to="appendTo">
-        <slot></slot>
-    </Teleport>
+    <template v-else-if="mounted">
+        <Teleport :to="appendTo">
+            <slot></slot>
+        </Teleport>
+    </template>
 </template>
 
 <script>
@@ -22,12 +24,17 @@ export default {
             default: false
         }
     },
+    data() {
+        return {
+            mounted: false
+        }
+    },
+    mounted() {
+        this.mounted = DomHandler.isClient();
+    },
     computed: {
         inline() {
             return this.disabled || this.appendTo === 'self';
-        },
-        isClient() {
-            return DomHandler.isClient();
         }
     }
 }