chore: Add more descriptive error for missing file system permission

plugins/storage/server/api/files.ts

@@ -47,7 +47,16 @@ router.post(
       throw AuthorizationError("Invalid key");
     }
 
-    await attachment.writeFile(file);
+    try {
+      await attachment.writeFile(file);
+    } catch (err) {
+      if (err.message.includes("permission denied")) {
+        throw Error(
+          `Permission denied writing to "${key}". Check the host machine file system permissions.`
+        );
+      }
+      throw err;
+    }
 
     ctx.body = {
       success: true,