terser 5.13.0 does not elide Array.includes ([].includes) calls which it is reasonably able to

[michaele-blend]

Feature request

Version 5.13.0

Complete CLI command or minify() options used

/** @returns {terser.MinifyOptions} */
const getTerserOpts = ({ debug }) => ({
  ecma: 2020,
  toplevel: false,

  parse: {},
  mangle: true,
  compress: {
    keep_fargs: false,

    pure_getters: true,
    drop_console: false,
    pure_funcs: [],

    unsafe: true,
    unsafe_arrows: true,
    unsafe_comps: true,
    unsafe_Function: true,
    unsafe_math: true,
    unsafe_symbols: true,
    unsafe_methods: true,
    unsafe_proto: true,

    passes: 10,

    global_defs: {
      DEBUG: debug,
    },
  },
  format: {
    comments: false,
    wrap_func_args: false,
    wrap_iife: false,
  },
});

const code = `
const DEBUG_assert = (expr, msg) => {
  if (!DEBUG) return;
  if (expr) return;
  throw new Error(msg);
};

const foo_test = (term) => {
  DEBUG_assert(Array.isArray(term), 'should be an array')
  DEBUG_assert([].includes(term), 'should be one of []')
}
`

const terser = require('terser');
terser.minify({ 'some-file.js': code }, getTerserOpts({ debug: true })).then(res => console.dir({ debug: true, ...res }))
terser.minify({ 'some-file.js': code }, getTerserOpts({ debug: false })).then(res => console.dir({ debug: false, ...res }))

terser input

see above

terser output or error

Expected result

when debug === true, I expect something to the effect of

{
  debug: true,
  code: 'const DEBUG_assert=(r,s)=>{if(!r)throw Error(s)},foo_test=r=>{DEBUG_assert(Array.isArray(r),"should be an array"),DEBUG_assert([].includes(r),"should be one of []")};'
}

when debug === false, I expect something to the effect of

{
  debug: false,
  code: 'const DEBUG_assert=()=>{},foo_test=s=>{};'
}

Actual

the debug === false case does not match my expectation. the actual output is

{
  debug: false,
  code: 'const DEBUG_assert=()=>{},foo_test=s=>{[].includes(s)};'
}

there is an additional [].includes() call which was kept.

[michaele-blend]

I just upgraded to latest (5.19.4, at time of writing), and my issue has disappeared. I now am able to enjoy the expected behavior.
did quick bisect, looks like #1330 fixed my issue; the resolution on this is to upgrade.