The following query's generated code for the Filter consists of the doEval() block which has redefinition of variable isNull which causes a compilation failure. Note that isNull is not even referenced in the generated code.
WHERE cast(columns as int) > 1
ANDcast(columns as varchar(20))='ASIA';
] < CompileException:[ Line 82, Column 28: Redefinition of local variable "isNull" ]"
I also get a Deadbuf access for this query, but that could be a separate issue.