Refactor UserLinkFromId component to enforce userId type and remove null checks

web/components/events/event-card.tsx

@@ -107,7 +107,7 @@ export function EventCard(props: {
         </p>
         {event.participants.length > 0 && (
           <div className="flex flex-wrap gap-1 mt-2">
-            {event.participants.map((participantId: any) => (
+            {event.participants.map((participantId: string) => (
               <span key={participantId} className="bg-canvas-100 text-ink-700 px-2 py-1 rounded text-xs">
                 <UserLinkFromId userId={participantId}/>
               </span>

web/components/events/user-link.tsx

@@ -32,10 +32,9 @@ export function UserLink({user, className = ""}: {
 }
 
 export function UserLinkFromId({userId, className = ""}: {
-  userId: string | null | undefined
+  userId: string
   className?: string
 }) {
-  if (!userId) return null
   const user = useUserInStore(userId)
   return <UserLink user={user} className={className}/>
 }