corner case with collapse_vars on undefined

[alexlamsl]

Bug report or feature request?

Bug report

ES5 or ES6+ input?

ES5

Uglify version (uglifyjs -V)

uglify-js 3.0.28

JavaScript input

var c = 0;

!function() {
    function f7() {
        var Math_1_1 = undefined;
        var undefined = Math_1_1++;
        try {
            !function f8(bar_1) {
                bar_1[true] = "foo";
            }();
        } catch (e) {
            c = c + 1;
        }
    }
    f7();
}();

console.log(c);

The uglifyjs CLI command executed or minify() options used.

uglifyjs test.js -b bracketize -c

JavaScript output or error produced.

$ echo test.js | node
1

$ uglifyjs test.js -b bracketize -c | node
0

[kzc]

Good to see the fuzzer is still finding bugs.

[alexlamsl]

@kzc indeed - though I'll need to wait for next weekend before trying to make a release again.