Angular Error: 'The NgModule needs to be compiled using the JIT compiler'

This error occurs when the JIT (Just-In-Time) compiler is not available for use in the Angular application. The JIT compiler is required to compile the 'MainModule' and its related components.

To resolve this error, you need to ensure that the '@angular/compiler' package is installed and available in your project. You can install this package by running the following command in your project directory:

npm install @angular/compiler

After the package is installed, make sure that it is imported into your 'AppModule' and any other modules that require it.

import { NgModule } from '@angular/core';
import { BrowserModule } from '@angular/platform-browser';
import { AppComponent } from './app.component';
import { MainModule } from './main/main.module';
import { Compiler } from '@angular/compiler';

@NgModule({
  declarations: [
    AppComponent
  ],
  imports: [
    BrowserModule,
    MainModule
  ],
  providers: [
    Compiler
  ],
  bootstrap: [AppComponent]
})
export class AppModule { }

By importing the 'Compiler' provider, you ensure that the JIT compiler is available to your application and can be used to compile the required modules.