revert: reverting "feat: preventing multiple calls of forRoot() in submodules loaded in async"

Author: willmendesneto

CHANGELOG.md

@@ -7,6 +7,14 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 
 ## [Unreleased][]
 
+### Fixed
+
+#### Breaking Change
+
+- Rolling back "Adding mechanism to prevents calling `forRoot()` more than once if module is loaded asynchronously in a submodule.". Unfortunately, this was affecting consumers and it needed to be reverted to avoid friction in other applications.
+
+If you need to have this feature in place, the suggestion is to create a specific module in your app and apply the changes on your application.
+
 ## [3.0.0][] - 2021-07-23
 
 ### Added

projects/ngx-skeleton-loader/src/lib/ngx-skeleton-loader.module.spec.ts

@@ -54,13 +54,4 @@ describe('NgxSkeletonLoaderModule method', () => {
     // tslint:disable-next-line: no-console
     expect(console.info).toHaveBeenCalledTimes(0);
   });
-
-  describe('When the module loaded twice asynchronously in a submodule', () => {
-    it('should throw an error if the module was previously loaded', () => {
-      expect(() => new NgxSkeletonLoaderModule(new NgxSkeletonLoaderModule())).toThrowError(
-        // tslint:disable-next-line: max-line-length
-        '`NgxSkeletonLoaderModule` is already loaded and it might cause issues. To avoid that, import the module only once in your app.',
-      );
-    });
-  });
 });

projects/ngx-skeleton-loader/src/lib/ngx-skeleton-loader.module.ts

@@ -1,4 +1,4 @@
-import { ModuleWithProviders, NgModule, Optional, SkipSelf } from '@angular/core';
+import { ModuleWithProviders, NgModule } from '@angular/core';
 import { CommonModule } from '@angular/common';
 
 import { NgxSkeletonLoaderComponent } from './ngx-skeleton-loader.component';
@@ -10,14 +10,6 @@ import { NgxSkeletonLoaderConfig, NGX_SKELETON_LOADER_CONFIG } from './ngx-skele
   exports: [NgxSkeletonLoaderComponent],
 })
 export class NgxSkeletonLoaderModule {
-  constructor(@Optional() @SkipSelf() parentModule?: NgxSkeletonLoaderModule) {
-    if (parentModule) {
-      throw new Error(
-        `\`NgxSkeletonLoaderModule\` is already loaded and it might cause issues. To avoid that, import the module only once in your app.`,
-      );
-    }
-  }
-
   static forRoot(config?: Partial<NgxSkeletonLoaderConfig>): ModuleWithProviders<NgxSkeletonLoaderModule> {
     return {
       ngModule: NgxSkeletonLoaderModule,