Example inputs that cause the problem

if (true) {
    const n = 42;
}

is obfuscated into

if(!![])const n=0x2a;

if (true) {
} else {
  let n = 42;
}

is obfuscated into

if(!![]){}else let n=0x2a;

When if or else clause contains only one statement, { and } are omitted in the obfuscated code and this makes a problematic sequence of words like if const <statement> or else let <statement>.

Steps to Reproduce

1. Access https://obfuscator.io/ and leave all the options default.
2. Obfuscate examples above.
3. Input the obfuscated code into Chrome console and see the result.

Your Environment

Chrome 83.0.4103.116 (Official Build) （64 bit） (cohort: Stable)