fix: prototype getting lost during deepmerge

.changeset/long-cougars-juggle.md

@@ -2,4 +2,5 @@
 "@zag-js/date-picker": patch
 ---
 
-Fix issue in Vue.js where input value could not be changed by typing.
+- Fix issue in Vue.js where input value could not be changed by typing.
+- Fix issue where setting controlled `min` and `max` values throws an error.

packages/core/src/deep-merge.ts

@@ -1,10 +1,10 @@
-import { compact, isObject } from "@zag-js/utils"
+import { compact, isPlainObject } from "@zag-js/utils"
 
 export function deepMerge<T extends Record<string, any>>(source: T, ...objects: T[]): T {
   for (const obj of objects) {
     const target = compact(obj)
     for (const key in target) {
-      if (isObject(obj[key])) {
+      if (isPlainObject(obj[key])) {
         if (!source[key]) {
           source[key] = {} as any
         }

packages/utilities/core/src/guard.ts

@@ -1,11 +1,24 @@
 export const isDev = () => process.env.NODE_ENV !== "production"
 export const isArray = (v: any): v is any[] => Array.isArray(v)
 export const isBoolean = (v: any): v is boolean => v === true || v === false
-export const isObject = (v: any): v is Record<string, any> => !(v == null || typeof v !== "object" || isArray(v))
+export const isObjectLike = (v: any): v is Record<string, any> => v != null && typeof v === "object"
+export const isObject = (v: any): v is Record<string, any> => isObjectLike(v) && !isArray(v)
 export const isNumber = (v: any): v is number => typeof v === "number" && !Number.isNaN(v)
 export const isString = (v: any): v is string => typeof v === "string"
 export const isFunction = (v: any): v is Function => typeof v === "function"
 export const isNull = (v: any): v is null | undefined => v == null
 
 export const hasProp = <T extends string>(obj: any, prop: T): obj is Record<T, any> =>
   Object.prototype.hasOwnProperty.call(obj, prop)
+
+const baseGetTag = (v: any) => Object.prototype.toString.call(v)
+const fnToString = Function.prototype.toString
+const objectCtorString = fnToString.call(Object)
+
+export const isPlainObject = (v: any) => {
+  if (!isObjectLike(v) || baseGetTag(v) != "[object Object]") return false
+  const proto = Object.getPrototypeOf(v)
+  if (proto === null) return true
+  const Ctor = hasProp(proto, "constructor") && proto.constructor
+  return typeof Ctor == "function" && Ctor instanceof Ctor && fnToString.call(Ctor) == objectCtorString
+}