chore: small readability improvement

src/shared/ensure.js

@@ -2,14 +2,15 @@ import isArray from './isArray'
 import { isObject } from './typeof'
 
 export function ensureIsArray(arg, key) {
-  if (key && isObject(arg)) {
+  if (isObject(arg) && key) {
     if (!isArray(arg[key])) {
       arg[key] = []
     }
+
     return arg
-  } else {
-    return isArray(arg) ? arg : []
   }
+
+  return isArray(arg) ? arg : []
 }
 
 export function ensuredPush(object, key, el) {