For Class-/Interface-Enhancements only one level of nesting allowed!

What causes this issue?

The nesting level of your enhancement implementation is deeper than the
maximum currently allowed.
Only for source code plug-ins we're supporting a deep nesting level.

System Response

The system issues an error message and will not allow you to continue with this transaction until the error is resolved.

How to fix this error?

Procedure for System Administrators

Error message extract from SAP system. Copyright SAP SE.