improve DeepPartial utility type

npm/ng-packs/packages/core/src/lib/models/utility.ts

@@ -1,8 +1,21 @@
+/* tslint:disable:ban-types */
 import { TemplateRef, Type } from '@angular/core';
 
-export type DeepPartial<T> = {
-  [P in keyof T]?: T[P] extends Record<string | number | symbol, any> ? DeepPartial<T[P]> : T[P];
-};
+export type DeepPartial<T> = Partible<T> extends never
+  ? T
+  : {
+      [K in keyof T]?: DeepPartial<T[K]>;
+    };
+
+type Partible<T> = T extends Primitive | Array<any>
+  ? never
+  : {
+      [K in keyof T]: T[K] extends Function ? never : T[K];
+    } extends T
+  ? T
+  : never;
+
+export type Primitive = undefined | null | boolean | string | number | bigint | symbol;
 
 export type InferredInstanceOf<T> = T extends Type<infer U> ? U : never;
 export type InferredContextOf<T> = T extends TemplateRef<infer U> ? U : never;