Resolve "Offline fallback page for django legacy pages is misleading in some situations"

Closes #838 (closed)

aleksis/core/frontend/components/celery_progress/CeleryProgress.vue

@@ -33,7 +33,7 @@
           </message-box>
         </div>
         <message-box
-          v-if="progress.state === 'ERROR'"
+          v-if="progress.state === 'FAILURE'"
           dense
           type="error"
           transition="slide-x-transition"
@@ -60,13 +60,13 @@
       <v-card-actions
         v-if="
           progress &&
-          (progress.state === 'ERROR' || progress.state === 'SUCCESS')
+          (progress.state === 'FAILURE' || progress.state === 'SUCCESS')
         "
       >
         <back-button :href="progress.meta.backUrl" text />
         <v-spacer />
         <v-btn
-          v-if="progress.meta.additionalButton"
+          v-if="progress.meta.additionalButton && progress.state === 'SUCCESS'"
           :href="progress.meta.additionalButton.url"
           text
           color="primary"
@@ -108,7 +108,7 @@ export default {
   },
   watch: {
     state(newState) {
-      if (newState === "SUCCESS" || newState === "ERROR") {
+      if (newState === "SUCCESS" || newState === "FAILURE") {
         this.$apollo.queries.celeryProgressByTaskId.stopPolling();
         this.$apollo.mutate({
           mutation: gqlCeleryProgressFetched,