ufuzz failure

[alexlamsl]

// original code
// (beautified)
var _calls_ = 10, a = 100, b = 10, c = 0;

export function f0(b) {
    try {
        {
            var brake2 = 5;
            do {
                switch ((a++ + -(b && (b[a++ + "foo"] ^= ("c" instanceof 3) + ("" ^ 25) !== (true - -4 !== (b = 3 + 0)))) || 4).toString()[b++]) {
                  case --b + (0 === 1 ? a : b):
                    break;

                  default:
                    {
                        var brake4 = 5;
                        while ({
                            Infinity: a++ + (b && typeof b.in == "function" && --_calls_ >= 0 && (/[abc4]/g.exec(((c = 1 + c, 
                            b && (b.then &= "foo" >>> 4 >= "" - [ , 0 ][1] < ((b && (b.__proto__ = "number" * [ , 0 ][1])) | 24..toString() > "undefined"))) || b || 5).toString()), 
                            b.in)()),
                            3: (c = c + 1) + --b,
                            static: (c = c + 1) + /[abc4]/.test(("number" in {
                                "-2"(bar_1, a_1) {
                                },
                                foo: (c = 1 + c, "undefined" + -3 >= (1 < true) !== 25 % NaN > 2 + {}),
                                async: (c = 1 + c, b += (null || this) - (24..toString() < 24..toString()) - (b = "function" - false - (/[a2][^e]+$/ >= 25)))
                            } || b || 5).toString()),
                            3: (c = c + 1) + b--,
                            "": ((b = (b |= (22 ^ 24..toString()) == (null === 25)) | ({} != "a" || "a" >> "")) || 4).toString()[typeof f2 == "function" && --_calls_ >= 0 && f2(1)]
                        } && --brake4 > 0) {
                            var expr5 = --b + {
                                set: --b + a--
                            };
                            for (var key5 in expr5) {
                                c = c + 1;
                            }
                        }
                    }
                    {
                        var brake7 = 5;
                        while (typeof f1 == "function" && --_calls_ >= 0 && f1("undefined") && --brake7 > 0) {
                            return;
                            typeof b == "function" && --_calls_ >= 0 && b("foo", NaN);
                        }
                    }
                    {
                        var expr9 = a++ + (b && b.done);
                        for (var key9 in expr9) {
                            try {
                                {
                                    var brake11 = 5;
                                    while (a++ + (b && typeof b.a == "function" && --_calls_ >= 0 && b.a``) && --brake11 > 0) {
                                        var expr12 = a++ + {
                                            [(c = 1 + c, (1 != Number(0xdeadn << 16n | 0xbeefn) === (c = c + 1, 
                                            /[a2][^e]+$/)) << ((NaN & true) <= ("object" && 0)))]: (c = 1 + c, 
                                            (c = c + 1, "b" === -3) !== ({} <= "number" || "object" % 25))
                                        }[c = 1 + c, key9 && (key9[a++ + ++a] = ([] == -3 & -2 === Infinity) != (key9 && ([ key9.c ] = [ ("b" ^ [ , 0 ][1]) + ("bar" - 3) ])))];
                                        for (var [ key12 ] in expr12) {
                                            {
                                                return c = 1 + c, ((1 ^ NaN) != (25 && 38..toString())) >> ("" + -0 > (undefined >= "number"));
                                            }
                                        }
                                    }
                                }
                            } finally {
                                {
                                    c = 1 + c, (b && (b[--b + (typeof b_1 == "undefined")] **= "c" | "object" | null + null)) === (5 >= /[a2][^e]+$/) + -1;
                                    c = 1 + c, (3 || 38..toString()) == (38..toString() !== NaN) || ("b" ^ NaN) >>> ([ , 0 ].length === 2 == 4);
                                }
                                c = c + 1;
                                if ((c = c + 1) + b--) {}
                                c = c + 1;
                            }
                        }
                    }

                  case a++ + (b && typeof b.next == "function" && --_calls_ >= 0 && b.next(..."" + b)):
                    if (/[abc4]/g.exec(((c = c + 1) + (typeof b == "function" && --_calls_ >= 0 && b(b--)) || b || 5).toString())) {
                        b ? +function() {}() : (c = c + 1) + --b;
                    }
                    break;

                  case 0 === 1 ? a : b:
                    break;
                }
            } while (typeof f0 == "function" && --_calls_ >= 0 && f0() && --brake2 > 0);
        }
    } catch (b_2) {
        {
            var brake23 = 5;
            L26976: while (--b + [].b && --brake23 > 0) {
                var brake24 = 5;
                do {
                    L26977: {
                        if (--b + [ (c = 1 + c, (NaN > -2) << ("foo" < 23..toString()) ^ -(38..toString() < [ , 0 ][1])), (c = 1 + c, 
                        (38..toString(), [ , 0 ][1]) - (/[a2][^e]+$/, 0) + (false ^ "bar" ^ 4 >>> this)), (c = 1 + c, 
                        (4 < "bar") + (3 - "c") || (null || 25) ^ (5 | -4)), (c = 1 + c, 
                        +(([ 3n ][0] > 2 === "a") + ([] & {}))), (c = 1 + c, (b_2 && (b_2.NaN >>>= (b && (b.c += [] < undefined)) === (b && (b.static >>>= ([ , 0 ].length === 2) + -2)))) ^ /[a2][^e]+$/ / -2 << (38..toString() & -4)) ]) {
                            -1;
                        } else {}
                        c = c + 1;
                    }
                } while (b_2 && --brake24 > 0);
            }
        }
    }
    {
        var brake30 = 5;
        while ({
            Infinity: --b + -0
        }[a++ + []] && --brake30 > 0) {
            return a++ + new function(b, bar, c_1) {
                {
                    return typeof b !== "string";
                }
            }();
        }
    }
    var foo_1 = 38..toString() in [ typeof f2 == "function" && --_calls_ >= 0 && f2(a++ + ([ (c = 1 + c, 
    (foo_1 += false === 3) * (b && (b[c = 1 + c, (b = ("foo" || "c") == ("function" & "c")) < void ([ 3n ][0] > 2) << void ([ , 0 ].length === 2)] >>= (-42n).toString() >> -2)) != (c = c + 1, 
    a_1 = [ , 0 ][1] == ([ , 0 ].length === 2))) ].var || 3).toString()[+((c = c + 1, 
    foo_1 <<= 3 < 1) ^ (this >> 38..toString()) - ("function" ^ Infinity))], --b + (typeof NaN_1 != "undefined")) ? (c = c + 1) + b-- : ~(((b && (b.undefined = [ , 0 ][1] | false)) + (false << [])) % (a_1 && (a_1.__proto__ += (c = c + 1, 
    false) < (undefined || [])))) ], a_1 = a++ + foo_1;
}

var b_2 = f0();

console.log(null, a, b, c, Infinity, NaN, undefined);

// uglified code
// (beautified)
var _calls_ = 10, a = 100, b = 10, c = 0;

function f0(b) {
    try {
        var brake2 = 5;
        do {
            switch ((a++ - (b && (b[a++ + "foo"] ^= 25 + ("c" instanceof 3) !== (5 != (b = 3)))) || 4).toString()[b++]) {
              case --b + b:
                break;

              default:
                for (var key5, brake4 = 5; a++, b && "function" == typeof b.in && 0 <= --_calls_ && (/[abc4]/g.exec((c = 1 + c, 
                (b && (b.then &= !0 < ((b && (b.__proto__ = NaN)) | "undefined" < 24..toString())) || b || 5).toString())), 
                b.in)(), --b, c = c + 1 + 1, /[abc4]/.test(("number" in {
                    "-2"(bar_1, a_1) {},
                    foo: !1 != 2 + {} < NaN,
                    async: (c = 1 + (c = 1 + c), b += this - (24..toString() < 24..toString()) - (b = NaN))
                } || b || 5).toString()), c += 1, ((b = --b | 0 == (22 ^ 24..toString()) | ("a" != {} || 0)) || 4).toString()["function" == typeof f2 && 0 <= --_calls_ && f2(1)], 
                0 < --brake4; ) {
                    for (key5 in --b + {
                        set: --b + a--
                    }) {
                        c += 1;
                    }
                }
                var key9, brake7 = 5;
                if ("function" == typeof f1 && 0 <= --_calls_ && f1("undefined") && 0 < --brake7) {
                    return;
                }
                for (key9 in a++ + (b && b.done)) {
                    try {
                        for (var key12, brake11 = 5; a++ + (b && "function" == typeof b.a && 0 <= --_calls_ && b.a``) && 0 < --brake11; ) {
                            for ([ key12 ] in a++ + {
                                [(c = 1 + c, (1 != Number(0xdeadn << 16n | 0xbeefn) === /[a2][^e]+$/) << !0)]: (c = 1 + (c += 1), 
                                !1 !== ({} <= "number" || NaN))
                            }[c = 1 + (c += 1), key9 && (key9[a++ + ++a] = (-3 == [] & !1) != (key9 && ([ key9.c ] = [ NaN ])))]) {
                                return c = 1 + c, (1 != 38..toString()) >> !1;
                            }
                        }
                    } finally {
                        c = 1 + c, b && (b[--b + ("undefined" == typeof b_1)] **= 0), 
                        c = 1 + c, 38..toString(), b--, c = (c += 1) + 1 + 1;
                    }
                }

              case a++ + (b && "function" == typeof b.next && 0 <= --_calls_ && b.next(..."" + b)):
                !/[abc4]/g.exec(((c += 1) + ("function" == typeof b && 0 <= --_calls_ && b(b--)) || b || 5).toString()) || b || (c += 1, 
                --b);
                break;

              case b:
            }
        } while ("function" == typeof f0 && 0 <= --_calls_ && f0() && 0 < --brake2);
    } catch (b_2) {
        for (var brake23 = 5; --b + [].b && 0 < --brake23; ) {
            for (var brake24 = 5; --b, c = 1 + c, 23..toString(), 38..toString(), 
            c = 1 + c, 38..toString(), c = 1 + (c = 1 + (c = 1 + c)), b_2 && (b_2.NaN >>>= (b && (b.c += [] < void 0)) === (b && (b.static >>>= (2 === [ , 0 ].length) + -2))), 
            38..toString(), c += 1, b_2 && 0 < --brake24; ) {}
        }
    }
    var brake30 = 5;
    if ({
        Infinity: --b
    }[a++ + []] && 0 < --brake30) {
        return a++ + new function(b, bar, c_1) {
            return !0;
        }();
    }
    var foo_1 = 38..toString() in [ "function" == typeof f2 && 0 <= --_calls_ && f2(a++ + ([ (c = 1 + c, 
    (foo_1 += !1) * (b && (b[c = 1 + c, (b = !1) < 0] >>= (-42n).toString() >> -2)) != (c += 1, 
    brake30 = 0 == (2 === [ , 0 ].length))) ].var || 3).toString()[c += 1, (foo_1 <<= !1) ^ this >> 38..toString()], --b + ("undefined" != typeof NaN_1)) ? (c += 1) + b-- : ~(((b && (b.undefined = 0)) + (!1 << [])) % (brake30 && (brake30.__proto__ += (c += 1, 
    !1 < [])))) ], brake30 = a++ + foo_1;
}

var b_2 = f0();

console.log(null, a, b, c, 1 / 0, NaN, void 0);

export {
    f0
};

original result:
null 166 10 990 Infinity NaN undefined

uglified result:
null 166 10 1001 Infinity NaN undefined

// reduced test case (output will differ)

// (beautified)
function f0() {
    var brake30;
    while (--brake30) {
        return 0;
    }
    var foo_1 = console.log() && (a_1 = 1) ? 0 : a_1.__proto__, a_1 = foo_1;
}

f0();
// output: TypeError: Cannot read property '__proto__' of undefined
// minify: 
// 
// options: {
//   "mangle": false,
//   "module": false,
//   "output": {
//     "v8": true
//   },
//   "validate": true
// }

minify(options):
{
  "mangle": false,
  "module": false,
  "output": {
    "v8": true
  }
}

Suspicious compress options:
  dead_code
  loops
  merge_vars