fix of #1042 rawlist throw

[SanariSan]

Fix of #1042

At the moment of pressing Enter key while Error being shown, index (1) which comes as an argument equals to empty string.
At the same time this.selected equals to undefined (2) here.

  getCurrentValue(index) { // (1)
    if (index == null) {
      index = this.rawDefault;
    } else if (index === '') {
      index = this.selected; // (2)
    } else {
      index -= 1;
    }

    const choice = this.opt.choices.getChoice(index); // (4)
    return choice ? choice.value : null;
  }

This happens because (3) here it gets undefined value every time non-existing index inserted, so at the time Error message shown, this value persists, which leads to assertion throw (4) here -> (5) here.

  onKeypress() {
    const index = this.rl.line.length ? Number(this.rl.line) - 1 : 0;


    if (this.opt.choices.getChoice(index)) {
      this.selected = index;
    } else {
      this.selected = undefined; // (3)
    }
    this.render();
  }

  getChoice(selector) {
    assert(_.isNumber(selector)); // (5)
    return this.realChoices[selector];
  }

To prevent this from happening I decided to re-assign (!) this.selected value if needed by checking with nullish coalescing operator.
This way, if user presses Enter without entering non-existing index beforehand (i.e. sending empty string), he gets the first (default) option selected, as it was before the change.
However, if Error been shown, this.selected will get -1 value, which is number (so assert pass + no negative effect) and allows user to press Enter as much as he would like to (nothing happens, expected behavior; alternative to -1 could be assigning this.rawDefault, then second Enter press just chooses first option available).
At the same time this allows to get back to selection by just pressing arrows or entering number.

getCurrentValue(index) {
    if (index == null) {
      index = this.rawDefault;
    } else if (index === '') {
      this.selected = this.selected ?? -1; // (!)
      index = this.selected;
    } else {
      index -= 1;
    }

    const choice = this.opt.choices.getChoice(index);
    return choice ? choice.value : null;
  }

[SBoudrias]

Thanks!

[hingsir]

Node v10 don't support Nullish coalescing operator this.selected = this.selected ?? -1

/usr/local/lib/node_modules/emrnvm/node_modules/inquirer/lib/prompts/rawlist.js:126
      this.selected = this.selected ?? -1;
                                     ^

SyntaxError: Unexpected token ?
    at Module._compile (internal/modules/cjs/loader.js:723:23)
    at Object.Module._extensions..js (internal/modules/cjs/loader.js:789:10)
    at Module.load (internal/modules/cjs/loader.js:653:32)
    at tryModuleLoad (internal/modules/cjs/loader.js:593:12)
    at Function.Module._load (internal/modules/cjs/loader.js:585:3)
    at Module.require (internal/modules/cjs/loader.js:692:17)
    at require (internal/modules/cjs/helpers.js:25:18)
    at Function.promptModule.restoreDefaultPrompts (/usr/local/lib/node_modules/emrnvm/node_modules/inquirer/lib/inquirer.js:65:36)
    at Object.inquirer.createPromptModule (/usr/local/lib/node_modules/emrnvm/node_modules/inquirer/lib/inquirer.js:72:16)
    at Object.<anonymous> (/usr/local/lib/node_modules/emrnvm/node_modules/inquirer/lib/inquirer.js:84:28)

Node Version 10.24.1

[yiyu-liao]

same error , my Node Version is v12.22.1