Merge branch '459-ui-bug-displaying-doi-when-there-is-none' into 'dev'

Fixed

See merge request !337

.docs/changelog.md

@@ -19,7 +19,8 @@ author: Martin Weise
 
 #### Changes
 
-* Remove the Data Database Sidecar and replace it with Apache Spark 4.
+* Remove the Data Database Sidecar and replace it with Apache Spark 4 
+  in [#458](https://gitlab.phaidra.org/fair-data-austria-db-repository/fda-services/-/issues/458).
 * Allow anonymous users to create subsets for public databases
   in [#449](https://gitlab.phaidra.org/fair-data-austria-db-repository/fda-services/-/issues/449).
 * Show file upload progress

dbrepo-ui/composables/identifier-service.ts

@@ -288,7 +288,7 @@ export const useIdentifierService = (): any => {
     if (!data) {
       return null
     }
-    return data.doi !== null ? 'DOI' : 'URI'
+    return data.doi ? 'DOI' : 'URI'
   }
 
   function creatorToCreatorJsonLd(creator: CreatorDto) {