fix(forkJoin): catch and forward selector errors (#3261)

* test(forkJoin): add selector error test

* fix(forkJoin): catch and forward selector errors

Closes #3216

Author: cartant

spec/observables/forkJoin-spec.ts

@@ -331,6 +331,20 @@ describe('Observable.forkJoin', () => {
     expectObservable(e1).toBe(expected);
   });
 
+  it('should raise error when the selector throws', () => {
+    function selector(x, y) {
+      throw 'error';
+    }
+
+    const e1 = Observable.forkJoin(
+               hot('--a-|'),
+               hot('---b-|'),
+               selector);
+    const expected = '-----#';
+
+    expectObservable(e1).toBe(expected);
+  });
+
   it('should allow unsubscribing early and explicitly', () => {
     const e1 =   hot('--a--^--b--c---d-| ');
     const e1subs =        '^        !    ';

src/internal/observable/ForkJoinObservable.ts

@@ -224,7 +224,13 @@ class ForkJoinSubscriber<T> extends OuterSubscriber<T, T> {
     }
 
     if (haveValues === len) {
-      const value = resultSelector ? resultSelector.apply(this, values) : values;
+      let value: any;
+      try {
+        value = resultSelector ? resultSelector.apply(this, values) : values;
+      } catch (err) {
+        destination.error(err);
+        return;
+      }
       destination.next(value);
     }