fix error handling in test saga

Jest used to define fail() but doesn't seem to do this anymore.
Replace it with throwing an error instead, which is basically the
same thing.

test/index.ts

@@ -22,7 +22,9 @@ export class AsyncSaga {
                 channel: this.channel,
                 dispatch: this.dispatch.bind(this),
                 getState: () => this.state,
-                onError: (e) => fail(e),
+                onError: (e, _i): void => {
+                    throw e;
+                },
             },
             saga,
         );
@@ -68,7 +70,9 @@ export class AsyncSaga {
         this.task.cancel();
         await this.task.toPromise();
         if (this.dispatches.some((x) => x.type !== END.type)) {
-            fail(`unhandled dispatches remain: ${JSON.stringify(this.dispatches)}`);
+            throw Error(
+                `unhandled dispatches remain: ${JSON.stringify(this.dispatches)}`,
+            );
         }
     }