Fix null scope

src/main/java/se/su/dsv/oauth2/admin/repository/ClientRow.java

@@ -15,6 +15,9 @@ public record ClientRow(
         String clientSecret)
 {
     public Set<String> scopeSet() {
+        if (scopes == null) {
+            return Set.of();
+        }
         return Arrays.stream(this.scopes.split(" "))
                 .filter(Predicate.not(String::isBlank))
                 .collect(Collectors.toUnmodifiableSet());