Apply suggestions from code review

Signed-off-by: Patrik Oldsberg <poldsberg@gmail.com>

.changeset/thick-donkeys-fold.md

@@ -2,4 +2,4 @@
 '@backstage/plugin-catalog': patch
 ---
 
-Fix for Diagram component using hardcoded namespace
+Fix for Diagram component using hard coded namespace.

plugins/catalog/src/components/SystemDiagramCard/SystemDiagramCard.tsx

@@ -157,7 +157,9 @@ export function SystemDiagramCard() {
         kind: ['Component', 'API', 'Resource', 'System', 'Domain'],
         'spec.system': [
           currentSystemName,
-          `${entity.metadata.namespace || ENTITY_DEFAULT_NAMESPACE}/${currentSystemName}`,
+          `${
+            entity.metadata.namespace || ENTITY_DEFAULT_NAMESPACE
+          }/${currentSystemName}`,
         ],
       },
     });