fix: disabled attribute fallback (#1984)

Co-authored-by: Dominik Pschenitschni <mail@celement.de>
Reviewed-on: https://kolaente.dev/vikunja/frontend/pulls/1984
Reviewed-by: konrad <k@knt.li>
Co-authored-by: Dominik Pschenitschni <dpschen@noreply.kolaente.de>
Co-committed-by: Dominik Pschenitschni <dpschen@noreply.kolaente.de>

src/views/list/ListKanban.vue

@@ -183,7 +183,7 @@
 			<div class="bucket new-bucket" v-if="canWrite && !loading && buckets.length > 0">
 				<input
 					:class="{'is-loading': loading}"
-					:disabled="loading || null"
+					:disabled="loading || undefined"
 					@blur="() => showNewBucketInput = false"
 					@keyup.enter="createNewBucket"
 					@keyup.esc="$event.target.blur()"

src/views/list/settings/edit.vue

@@ -12,7 +12,7 @@
 			<div class="control">
 				<input
 					:class="{ 'disabled': listService.loading}"
-					:disabled="listService.loading || null"
+					:disabled="listService.loading || undefined"
 					@keyup.enter="save"
 					class="input"
 					id="title"