Incorrect async transform

[breezewish]

// esbuild --bundle index.ts --outfile=out.js --target=es2015

const myFunc = function (c) {
  return {
    foo: async (message, options = {}) => {
      if (message.a !== "1") {
        throw new Error("foo");
      }
      console.log("Pass!");
    },
  };
};

myFunc({}).foo({ a: "1" });

The snippet above will throw an error instead of printing "Pass" after esbuild transformation.

The transformed result is:

(() => {
  var __async = (__this, __arguments, generator) => {
    return new Promise((resolve, reject) => {
      var fulfilled = (value) => {
        try {
          step(generator.next(value));
        } catch (e) {
          reject(e);
        }
      };
      var rejected = (value) => {
        try {
          step(generator.throw(value));
        } catch (e) {
          reject(e);
        }
      };
      var step = (result) => {
        return result.done ? resolve(result.value) : Promise.resolve(result.value).then(fulfilled, rejected);
      };
      step((generator = generator.apply(__this, __arguments)).next());
    });
  };

  // src/index.ts
  const myFunc = function(c) {
    return {
      foo: (_0) => __async(this, arguments, function* (message, options = {}) {
        //                       ^^^^^^^^^
        // Notice that `arguments` here is incorrect, since arrow function does
        // not provide arguments.
        if (message.a !== "1") {
          throw new Error("foo");
        }
        console.log("Pass!");
      })
    };
  };
  myFunc({}).foo({a: "1"});
})();

[rtsao]

It looks like this regression was introduced in v0.6.32 via d121b38

Which makes sense because removing options = {} from your example fixes the issue.