Silly problem when using istanbul with real arrow functions

[richtera]

When instrumenting code for code coverage there will be additional operations injected into real arrow functions associated with derive. Since derive doesn't support SequenceExpressions this causes a weird error, that has really no solutions other than either rewriting the code using symbolic string expressions or excluding the whole file from code coverage. I am wondering if by default SequenceExpressions could just be evaluated as the last Expression in the list or maybe some hook to override the functionality of SequenceExpressions?

[richtera]

Ref https://docs.cypress.io/guides/tooling/code-coverage#Using-NYC The instrumentation will put additional ++someglobal[LINE] into the code so when toString() looks at the arrow function it will see additional ++ operation inside of the code segment before parsing it and generating a SequenceExpression.