Hide link button on DataFiles when the S3 URL is unavailable

src/components/Imports/Files/File.vue

@@ -39,7 +39,7 @@
           class="button is-text has-text-primary"
           :href="file.s3_url"
           target="_blank"
-          v-if="file.progress === undefined && file.status === 'checked'"
+          v-if="file.progress === undefined && file.status === 'checked' && file.s3_url !== null"
         >
           <span class="icon is-small">
             <i class="icon-link"></i>