DDLS: Fix dump during serialization (#4371)
DDLS: Fix dump during serialization (#4371)

The specific dump occurred when the source was empty. Now it checks the string length properly.

Closes #4309

Co-authored-by: Lars Hvam <721d1b171982cd84b755f6b25130d2b88cd1f696@hotmail.com>
sbcgua/abapGit,larshp/abapGit,sbcgua/abapGit,larshp/abapGit