Thanks -- this looks really nice and I'm glad you did it.

I'm trying to also improve code coverage across the board, and from running "./gradlew testCodeCoverageReport" I can see that there are a few spots in IRFactory that we aren't testing. Specifically, there's some new exception-handling code around line 129 of IRFactory.java that doesn't seem to be hit by any of the tests. Would it be possible for you to come up with some sort of test code that would help us hit that spot?

Specifically, from looking at the coverage report, the part below in "transformTree" is new code, it seems pretty important, and it seems to be missing coverage.

    ScriptNode script = null;
    astNodePos.push(root);
    try {
        script = (ScriptNode) transform(root);
    } catch (Parser.ParserException e) {
        // Doesn't seem to have any code coverage here...
        parser.reportErrorsIfExists(root.getLineno());
        return null;
    } finally {
        astNodePos.pop();
    }

Thanks!

@gbrail I added test to see if runtimeError was called ref. 6480350. However, the result of ./gradlew testCodeCoverageReport did not change. What should I do?

Hi @tuchida while rummaging though the backlog of issues, I ran into the following issues of which I wonder if this PR either resolved them or at least moves the needle somewhat:

• FAILED ASSERTION due to malformed destructuring syntax #405
• ClassCastException when compiling malformed destructuring expression #406
• const [y, y] = [] throws a TypeError, instead of SyntaxError #989
• Error with destructuring array assignment(?) #1187

@p-bakker #405 was fixed. Others remained the same or had other errors.

This is great and thanks for doing it!