Tiny TypeScript update follow-up

Author: andywer

package.json

@@ -72,6 +72,8 @@
     "observable-fns": "^0.5.1"
   },
   "devDependencies": {
+    "@rollup/plugin-commonjs": "^16.0.0",
+    "@rollup/plugin-node-resolve": "^10.0.0",
     "@types/chai": "^4.2.14",
     "@types/debug": "^4.1.5",
     "@types/execa": "^2.0.0",
@@ -88,8 +90,6 @@
     "raw-loader": "^4.0.2",
     "rimraf": "^3.0.2",
     "rollup": "^2.32.1",
-    "@rollup/plugin-commonjs": "^16.0.0",
-    "@rollup/plugin-node-resolve": "^10.0.0",
     "threads-plugin": "^1.3.3",
     "tiny-worker": "^2.2.0",
     "ts-loader": "^8.0.7",

src/master/pool.ts

@@ -271,7 +271,7 @@ class WorkerPool<ThreadType extends Thread> implements Pool<ThreadType> {
         next(event) {
           if (event.type === PoolEventType.taskQueueDrained) {
             subscription.unsubscribe()
-            resolve()
+            resolve(void 0)
           }
         },
         error: reject     // make a pool-wide error reject the completed() result promise