> Your assumption that TclListObjGetElements() always results in a list object is wrong: In case of an empty string representation the empty string is returned.

You are right Jan, Thx.
<pre>
#define [/artifact?udc=1&name=688b67d0c051138d&ln=2403-2406&r=core-8-6-branch|TclListObjGetElements](interp, listPtr, objcPtr, objvPtr) \
    (((listPtr)->typePtr == &tclListType) \
	    ? ((ListObjGetElements((listPtr), *(objcPtr), *(objvPtr))), TCL_OK)\
	    : Tcl_ListObjGetElements((interp), (listPtr), (objcPtr), (objvPtr)))
</pre>
How one can see here, the object either already a list or (my assumtion was) it will be to list immeadiatelly after invocation of Tcl_ListObjGetElements.

Just I really overlooked this block in scope it is not a list -

Thank you again.
I'll try to construct a test-case for exacly this situation.