Showcasing babel+fast-async issue

.babelrc

{
  "presets": [
    [ "@babel/env", {
      // "loose": true,
      "exclude":
        ["transform-regenerator", "transform-async-to-generator"]
      }
    ]
  ],

  "plugins": [
    "module:fast-async"
  ]
}

entry.js

async function executeTasks(tasks) {
  for (const taskName of tasks) {
    try {
      await executeCommands()
    } catch (error) {
      console.error("Error")
    }
  }
}

output-loose-mode.js

"use strict";

function executeTasks(tasks) {
  return new Promise(function ($return, $error) {
    var _iterator, _isArray, _i, _ref, taskName;

    _iterator = tasks, _isArray = Array.isArray(_iterator), _i = 0, _iterator = _isArray ? _iterator : _iterator[Symbol.iterator]();
    var $Loop_2_trampoline;

    function $Loop_2() {
      if (true) {
        if (_isArray) {
          if (_i >= _iterator.length) return [1];
          _ref = _iterator[_i++];
        } else {
          _i = _iterator.next();
          if (_i.done) return [1];
          _ref = _i.value;
        }

        taskName = _ref;

        var $Try_1_Post = function () {
          try {
            return $Loop_2;
          } catch ($boundEx) {
            return $error($boundEx);
          }
        };

        var $Try_1_Catch = function (error) {
          try {
            console.error("Error");
            return $Try_1_Post();
          } catch ($boundEx) {
            return $error($boundEx);
          }
        };

        try {
          return Promise.resolve(executeCommands()).then(function ($await_4) {
            try {
              return $Try_1_Post();
            } catch ($boundEx) {
              return $Try_1_Catch($boundEx);
            }
          }, $Try_1_Catch);
        } catch (error) {
          $Try_1_Catch(error)
        }
      } else return [1];
    }

    return ($Loop_2_trampoline = function (q) {
      while (q) {
        if (q.then) return void q.then($Loop_2_trampoline, $error);

        try {
          if (q.pop) {
            if (q.length) return q.pop() ? $Loop_2_exit.call(this) : q;else q = $Loop_2;
          } else q = q.call(this);
        } catch (_exception) {
          return $error(_exception);
        }
      }
    }.bind(this))($Loop_2);

    function $Loop_2_exit() {
      return $return();
    }
  });
}

package.json

{
  "name": "test-async-babel",
  "version": "1.0.0",
  "description": "",
  "main": "index.js",
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1"
  },
  "keywords": [],
  "author": "",
  "license": "ISC",
  "dependencies": {
    "@babel/cli": "^7.0.0-beta.46",
    "@babel/core": "^7.0.0-beta.46",
    "@babel/preset-env": "^7.0.0-beta.46",
    "fast-async": "^7.0.5",
    "nodent-transform": "^3.2.3"
  }
}

stack-trace-without-loose-mode.txt

TypeError: Cannot read property 'length' of undefined
    at Buffer._append (/Users/swerner/test-async-babel/node_modules/@babel/generator/lib/buffer.js:115:26)
    at Buffer.append (/Users/swerner/test-async-babel/node_modules/@babel/generator/lib/buffer.js:81:10)
    at Generator._append (/Users/swerner/test-async-babel/node_modules/@babel/generator/lib/printer.js:202:52)
    at Generator.word (/Users/swerner/test-async-babel/node_modules/@babel/generator/lib/printer.js:126:10)
    at Generator.Identifier (/Users/swerner/test-async-babel/node_modules/@babel/generator/lib/generators/types.js:43:8)
    at /Users/swerner/test-async-babel/node_modules/@babel/generator/lib/printer.js:315:23
    at Buffer.withSource (/Users/swerner/test-async-babel/node_modules/@babel/generator/lib/buffer.js:178:28)
    at Generator.withSource (/Users/swerner/test-async-babel/node_modules/@babel/generator/lib/printer.js:182:15)
    at Generator.print (/Users/swerner/test-async-babel/node_modules/@babel/generator/lib/printer.js:314:10)
    at Generator.printJoin (/Users/swerner/test-async-babel/node_modules/@babel/generator/lib/printer.js:382:12)