handle bot users properly

Signed-off-by: Fredrik Adelöw <freben@gmail.com>

.changeset/red-parrots-attack.md

@@ -0,0 +1,5 @@
+---
+'@backstage/plugin-catalog-backend-module-gitlab': patch
+---
+
+Fix a corner case where returned users are null for bots

plugins/catalog-backend-module-gitlab/src/lib/client.ts

@@ -128,10 +128,11 @@ export class GitLabClient {
         throw new Error(`GraphQL errors: ${JSON.stringify(response.errors)}`);
       }
       memberIds.push(
-        ...response.data.group.groupMembers.nodes.map(
-          (node: { user: { id: string } }) =>
+        ...response.data.group.groupMembers.nodes
+          .filter(n => n.user)
+          .map(node =>
             Number(node.user.id.replace(/^gid:\/\/gitlab\/User\//, '')),
-        ),
+          ),
       );
       ({ hasNextPage, endCursor } = response.data.group.groupMembers.pageInfo);
     } while (hasNextPage);