fix(action-listener-middleware): typo

Author: FaberVitale

packages/action-listener-middleware/src/index.ts

@@ -55,7 +55,7 @@ function assertFunction(
   expected: string
 ): asserts func is (...args: unknown[]) => unknown {
   if (typeof func !== 'function') {
-    throw new TypeError(`${expected} in not a function`)
+    throw new TypeError(`${expected} is not a function`)
   }
 }