refactor: cleanup isFunction() helper implementation

Signed-off-by: Jérôme Benoit <[email protected]>

src/benchmark.js

@@ -340,6 +340,7 @@ export async function run(opts = {}) {
     throw new TypeError(
       `expected function as 'now' option, got ${opts.now.constructor.name}`
     )
+
   opts.silent = opts.silent ?? false
   opts.units = opts.units ?? false
   opts.colors = opts.colors ?? colors

src/utils.js

@@ -1,5 +1,5 @@
 export const isFunction = fn => {
-  return [Function, AsyncFunction].includes(fn.constructor)
+  return typeof fn === 'function'
 }
 
 export const AsyncFunction = (async () => {}).constructor