multiple: check when var is possibly undefined

In cases where a field on an object might be undefined,
rather omit the value than set the field to undefined.

src/Components/CreateImageWizard/utilities/checkRepositoriesAvailability.ts

@@ -64,7 +64,7 @@ export const useCheckRepositoriesAvailability = () => {
     // Transform the fresh repos array into a Set to access its elements in O(1)
     // complexity later in the for loop.
     const freshReposUrls = new Set(
-      freshRepos.data?.map((freshRepo) => freshRepo.url)
+      freshRepos?.data?.map((freshRepo) => freshRepo.url)
     );
     for (const customRepo of customRepositories) {
       if (customRepo.baseurl && !freshReposUrls.has(customRepo.baseurl[0])) {