Remove regenerator finished generator error

lib/6to5/transformation/transformers/es6-generators/runtime.js

@@ -87,9 +87,7 @@ function Generator(innerFn, outerFn, self, tryList) {
       throw new Error("Generator is already running");
     }
 
-    if (state === GenStateCompleted) {
-      throw new Error("Generator has already finished");
-    }
+    var alreadyFinished = state === GenStateCompleted;
 
     while (true) {
       var delegate = context.delegate;
@@ -162,7 +160,8 @@ function Generator(innerFn, outerFn, self, tryList) {
       state = GenStateExecuting;
 
       try {
-        var value = innerFn.call(self, context);
+        var value;
+        if (!alreadyFinished) value = innerFn.call(self, context);
 
         // If an exception is thrown from innerFn, we leave state ===
         // GenStateExecuting and loop back for another invocation.
@@ -267,6 +266,10 @@ runtime.keys = function (object) {
   };
 };
 
+function isIn(key, obj) {
+  return typeof obj !== "string" && typeof obj !== "number" && key in obj;
+}
+
 function values(iterable) {
   var iterator = iterable;
   if (iteratorSymbol in iterable) {

test/_generator-helpers.js

@@ -20,14 +20,6 @@ exports.raise = function raise(argument) {
 };
 
 exports.assertAlreadyFinished = function assertAlreadyFinished(generator) {
-  try {
-    generator.next();
-    assert.ok(false, "should have thrown an exception");
-  } catch (err) {
-    assert.ok(err instanceof Error);
-    assert.strictEqual(
-      err.message,
-      "Generator has already finished"
-    );
-  }
+  var item = generator.next();
+  assert.ok(item.done && item.value === undefined, "not finished");
 };

test/fixtures/transformation/es6-generators/function-declaration-hoisting-should-work-even-if-the-declarations-are-out-of-order/exec.js

@@ -15,18 +15,10 @@ function *gen(n) {
     function decrement(x) {
       return x - 1;
     }
-  } else {
-    // The behavior of function declarations nested inside conditional
-    // blocks is notoriously underspecified, and in V8 it appears the
-    // halve function is still defined when we take this branch, so
-    // "undefine" it for consistency with regenerator semantics.
-    halve = void 0;
   }
 
-  yield typeof halve;
-
   yield increment(increment(n));
 }
 
-genHelpers.check(gen(3), [4, 1, "function", 5]);
-genHelpers.check(gen(4), [5, "undefined", 6]);
+genHelpers.check(gen(3), [4, 1, 5]);
+genHelpers.check(gen(4), [5, 6]);