3565443 - Tasklist run of SAP_BW4_BEFORE_UPGRADE generates SYNTAX_ERROR dump on Program RSUPGRCHECK

During the SAP_BW4_BEFORE_UPGRADE run (which is using the Task CL_RSO_UPGR_DDIC_CHECK too) an ST22 dump is being generated like the one below :

Category               ABAP programming error
Runtime Errors         SYNTAX_ERROR
ABAP Program           RSUPGRCHECK
Application Component  BW4-ME

Short Text
    Syntax error in program "RSUPGRCHECK

What happened?
    Error in the ABAP application program.

    The current ABAP program "CL_RSO_UPGR_DDIC_CHECK========CP" had to be
     terminated because it found a
    statement that could not be executed.
    In include "RSUPGRCHECK                             ", in line 36 of program
     "RSUPGRCHECK                             ", the following syntax errors
    have occurred:
    Type "RSISOSMAP" is unknown.

BW/4HANA 2.0 < SP14

upgrade, syntax error , KBA , BW4-ME , Metadata (Design time) , Problem