Jenkins groovy.lang.MissingPropertyException:

Using Jenkins
1

I have changed few lines in my Jenkins groovy,

                if(RESULT_BUILD_SUCCESS == postBuildErrorLevel){

                    postBuildErrorLevel += bat returnStatus: true, script:"${pipelineParams.FLAWFINDER_EXE} --html --context . > ${BUILD_OUTPUT_ABS_DIR}\\\\Flawfinder\_${PROJECT_NAME}\_rev\_${BRANCH_REVISION.take(7)}.html"

                }

I get error as,
groovy.lang.MissingPropertyException: No such property: working for class: groovy.lang.Binding

Can someone please help here?

Jenkins setup: