3271404 - BW query execution fails with a "type error in expression evaluator" error message

A BW query is based on a HANA composite provide which is build on a HANA calculation view with direct mappings. Executing the query results in the following error:

Error 6.970 has occurred in the BWA/SAP HANA server  
Error message  Object Collapsed Object Name = "SAPHANADB"."0BW:BIA:BI0_0Q....__CS", FM Name = TREX_DBS_AGGREGATE]  
Error message  Object Collapsed '00000000', "...._KEY__BASE_ATTR__")(6970),QueryId:....:DUM/[Request Info: ...  
Error message  Object Collapsed string('00000000'))': Evaluator: type error in expression evaluator;[here]if(isnull("....__BASE_ATT ...  

The Indexserver trace shows the following: 

[79726]\{358198\}[-1/-1] 2022-11-03 13:17:15.059180 e itab             ExpressionColumn.cpp(01129) : exception  1: no.70006970  (AttributeEngine/ExpressionColumn.cpp:1129) TID: 79726
    Evaluator: type error in expression evaluator; $message$=unable to create expressioncolumn 'coalesce("...__BASE_ATTR__", string('00000000'))': Evaluator: type error in expression evaluator;[here]if(isnull("...__BASE_ATTR__"), '00000000', "...__BASE_ATTR__")(6970)

• SAP BW/4HANA and higher
• SAP HANA Database

KBA , BW4-DM-HCPR , Composite Provider , BW-BEX-OT-HCPR , CompositeProvider Query , Problem