[fix]: id checking while register with namespace=""

[Pratap2018]

🎯 Purpose

FIX:

Error: failed to execute message; message index: 0: expected number of did id elements for mainnet to be 3, got 4:   invalid schema Id
     at SchemaRpc.<anonymous> (src/schema/schemaRPC.ts:81:13)
     at Generator.next (<anonymous>)
     at fulfilled (src/schema/schemaRPC.ts:33:58)
     at processTicksAndRejections (node:internal/process/task_queues:95:5)

---

📝 Changes

• Brief list of main updates

---

🔄 Type

• 🚀 Feature
• 🐛 Fix
• 📝 Docs
• ♻️ Refactor
• ✅ Tests
• 🔧 Config / CI

---

🧪 Testing

How did you test this? (unit/integration/manual)

---

✅ Checklist

• Code follows Hypermine standards
• Tests/docs updated if needed
• Verified locally