SAP Message 5P377 - The node under the feature cannot be an error operation

Diagnosis
Rules for the second hierarchy level:
- Just one node is allowed, but no error operations.
- If a main feature has field or table return, two nodes are allowed
if one node is a debugging operation.
- If a main feature has table return, a maximum of 36 nodes are
allowed if all of the nodes contain return lines, or a maximum of
35 return lines and just one debugging operation.
- A subfeature is allowed a maximum of 36 nodes if all of the nodes
contain return lines or program markers, or 35 and just one
debugging operation.