Fix undefined of id of error plugin field

[ZaykaNya]

Describe the bug 👀

Fix undefined of id of error plugin field

How to reproduce 🏃:

1. Go to Create Plugin Page
2. Create some fields with errors.
3. Click Save.
4. In console see that ids are undefined.

Expected behavior 🙌

getNested() function returns normal ids of field instead of undefined.

Screenshots ✨

System information

Desktop 💻:

• OS: [e.g. iOS]
• Browser [e.g. chrome, safari]
• Version [e.g. 22]

Smartphone 📱:

• Device: [e.g. iPhone6]
• OS: [e.g. iOS8.1]
• Browser [e.g. stock browser, safari]
• Version [e.g. 22]

Additional context 🌞