org_members: Display username as fallback

When displaying members in the organization members list, the username
will now be used as a fallback if the email and full name are not
available. This ensures a consistent display of user identifiers.

Author: sluongng

enterprise/app/org/org_members.tsx

@@ -250,7 +250,8 @@ export default class OrgMembersComponent extends React.Component<OrgMembersProps
         <div className="affected-users-list">
           {selectedMembers.map((member) => (
             <div className={`affected-users-list-item ${this.isLoggedInUser(member) ? "flagged-self-user" : ""}`}>
-              {member?.user?.email || member?.user?.name?.full} {iconFromAccountType(member.user?.accountType)}
+              {member?.user?.email || member?.user?.name?.full || member?.user?.username}{" "}
+              {iconFromAccountType(member.user?.accountType)}
             </div>
           ))}
         </div>