fix access to form in checkValidity

dashboard/src/components/AppImportDialog.vue

@@ -25,8 +25,8 @@ const encryptionPassword = ref('');
 const encryptedFilenames = ref(false);
 
 const isFormValid = ref(false);
-function validateForm() {
-  isFormValid.value = form.value && form.value.checkValidity();
+function checkValidity() {
+  isFormValid.value = form.value ? form.value.checkValidity() : false;
 }
 
 async function onSubmit() {
@@ -251,7 +251,7 @@ function onBackupConfigChanged(event) {
       }
     }
 
-    setTimeout(validateForm, 100); // update state of the confirm button
+    setTimeout(checkValidity, 100); // update state of the confirm button
   };
 
   reader.readAsText(event.target.files[0]);
@@ -262,7 +262,7 @@ function onUploadBackupConfig() {
 }
 
 watchEffect(() => {
-  if (providerConfig.value.credentials) setTimeout(validateForm, 100);
+  if (providerConfig.value.credentials) setTimeout(checkValidity, 100);
 });
 
 defineExpose({
@@ -310,7 +310,7 @@ defineExpose({
           </button>
         </p>
 
-        <form @submit.prevent="onSubmit()" autocomplete="off" ref="form" @input="validateForm()">
+        <form @submit.prevent="onSubmit()" autocomplete="off" ref="form" @input="checkValidity()">
           <fieldset :disabled="busy">
             <input style="display: none;" type="submit"/>