fix: add defensive type checks to prevent React error 31

- Add type guards in nip89-helpers to ensure string types
- Check metadata object structure before accessing properties
- Add fallbacks for undefined address.identifier values
- Prevents accidentally rendering objects as React children

src/components/nostr/kinds/HandlerRecommendationDetailRenderer.tsx

@@ -61,7 +61,7 @@ function HandlerCard({
         <div className="flex items-center gap-2">
           <Package className="size-5 text-muted-foreground" />
           <span className="text-sm text-muted-foreground">
-            Loading {address.identifier}...
+            Loading {address?.identifier || "handler"}...
           </span>
         </div>
       </div>

src/components/nostr/kinds/HandlerRecommendationRenderer.tsx

@@ -46,7 +46,9 @@ function HandlerItem({
 }) {
   const { addWindow } = useGrimoire();
   const handlerEvent = useNostrEvent(address);
-  const appName = handlerEvent ? getAppName(handlerEvent) : address.identifier;
+  const appName = handlerEvent
+    ? getAppName(handlerEvent)
+    : (address?.identifier || "Unknown Handler");
 
   const handleClick = () => {
     addWindow("open", { pointer: address });

src/lib/nip89-helpers.ts

@@ -32,7 +32,9 @@ export function getAppName(event: NostrEvent): string {
   if (event.content) {
     try {
       const metadata = JSON.parse(event.content);
-      if (metadata.name) return metadata.name;
+      if (metadata && typeof metadata === "object" && metadata.name && typeof metadata.name === "string") {
+        return metadata.name;
+      }
     } catch {
       // Not valid JSON, continue to fallback
     }
@@ -40,7 +42,7 @@ export function getAppName(event: NostrEvent): string {
 
   // Fallback to d tag identifier
   const dTag = getTagValue(event, "d");
-  return dTag || "Unknown App";
+  return dTag && typeof dTag === "string" ? dTag : "Unknown App";
 }
 
 /**
@@ -51,10 +53,13 @@ export function getAppDescription(event: NostrEvent): string | undefined {
 
   try {
     const metadata = JSON.parse(event.content);
-    return metadata.description;
+    if (metadata && typeof metadata === "object" && metadata.description && typeof metadata.description === "string") {
+      return metadata.description;
+    }
   } catch {
-    return undefined;
+    // Invalid JSON
   }
+  return undefined;
 }
 
 /**
@@ -65,10 +70,16 @@ export function getAppImage(event: NostrEvent): string | undefined {
 
   try {
     const metadata = JSON.parse(event.content);
-    return metadata.image || metadata.picture;
+    if (metadata && typeof metadata === "object") {
+      const image = metadata.image || metadata.picture;
+      if (image && typeof image === "string") {
+        return image;
+      }
+    }
   } catch {
-    return undefined;
+    // Invalid JSON
   }
+  return undefined;
 }
 
 /**