Expression Rule Error invalid index: Cannot index property 'status' of type String into type list) (Data Outputs)

Hi,

Facing below error while executing the Expression rule -

Expression evaluation error in rule '<Rule Name>' (called by rule '<Rule Name>') at function 'reduce' [line 10]invalid index: Cannot index property 'status' of type String into type list) (Data Outputs)

The expression rule code is 

cast(
typeof(ri!cdt),
reduce(
a!update(data: _, index: _, value: _),
ri!cdt,
merge(ri!fields, ri!newValues)
)
)

Please help what is missing.

Thanks in advance