Angular - Type Pipe does not have 'ɵmod' property

Question

I am attempting to create a custom pipe that would return a sum of an array in a table, but for whatever reason, Angular is complaining about my pipe not having an 'emod' property.

My pipe:

import { Injectable, Pipe, PipeTransform } from '@angular/core';

@Pipe({
  name: 'fieldSum',
  pure: false
})
@Injectable()
export class FieldSumPipe implements PipeTransform {
  transform(items: any[], attr: string): number {
    return items.reduce((a, b) => a + b[attr], 0);
  }
}

My module:

import { SomeComponent} from './some.component';
import { SomeRoutingModule} from './some-routing.module';
import { FieldSumPipe } from '../../../shared/pipes/fieldsum.pipe';
// Other imports...

@NgModule({
    imports: [
        CommonModule,
        SomeRoutingModule,
        FieldSumPipe, // other imports removed for brevity
    ],
    declarations: [
        SomeComponent,
    ],
    exports: [
        FieldSumPipe
    ]
})
export class SomeModule { }

My component HTML:

      <table class="table table-striped table-hover table-responsive-lg" [mfData]="tableData" #mf="mfDataTable" [mfRowsOnPage]="10">
        <thead>
          <tr>
            <th>...</th>
            <th>...</th>
            <th>...</th>
            <th>Profit</th>
          </tr>
        </thead>
        <tbody>
          <tr *ngFor="let item of mf.data">
            <td>{{ item.Id }}</td>
            <td>{{ item.Name }}</td>
            <td>{{ item.Something }}</td>
            <td>{{ item.Profit }}</td>
          </tr>
        </tbody>
        <tfoot>
          <tr>
            <td></td>
            <td></td>
            <td></td>
            <td>{{ mf.data | fieldSum:'Profit' }}</td>
          </tr>
        </tfoot>
      </table>

VS Code is claiming that The pipe 'fieldSum' could not be found, but it does compile everything successfully and it manages to open in browser. However, when I click on whatever is supposed to load my component, the console displays an error.

core.js:4442 ERROR Error: Uncaught (in promise): Error: Type FieldSumPipe does not have 'ɵmod' property.
Error: Type FieldSumPipe does not have 'ɵmod' property.
    at getNgModuleDef (core.js:1855)
    at recurse (core.js:24235)
    at recurse (core.js:24246)
    at registerNgModuleType (core.js:24231)
    at new NgModuleFactory$1 (core.js:24345)
    at Compiler_compileModuleSync__POST_R3__ (core.js:27135)
    at Compiler_compileModuleAsync__POST_R3__ [as compileModuleAsync] (core.js:27140)
    at MergeMapSubscriber.project (router.js:3506)
    at MergeMapSubscriber._tryNext (mergeMap.js:44)
    at MergeMapSubscriber._next (mergeMap.js:34)
    at resolvePromise (zone-evergreen.js:798)
    at resolvePromise (zone-evergreen.js:750)
    at zone-evergreen.js:860
    at ZoneDelegate.invokeTask (zone-evergreen.js:399)
    at Object.onInvokeTask (core.js:27533)
    at ZoneDelegate.invokeTask (zone-evergreen.js:398)
    at Zone.runTask (zone-evergreen.js:167)
    at drainMicroTaskQueue (zone-evergreen.js:569)

I am not sure if it's related in any way, but my SomeModule is lazy loaded in the AppRoutingModule.

import { NgModule } from '@angular/core';
import { Routes, RouterModule } from '@angular/router';

const routes: Routes = [
  {
    path: '',
    data: {
      title: 'Whatever',
    },
    children: [
      {
        path: 'some',
        loadChildren: () =>
        import('./some/some.module').then((m) => m.SomeModule),
      }
    ]
  },
];

@NgModule({
  imports: [RouterModule.forChild(routes)],
  exports: [RouterModule],
})
export class AppRoutingModule {}

Answer 1

As it turns out, the solution was to to put the FieldSumPipe in the declarations and exports of my module rather than the imports.

import { SomeComponent} from './some.component';
import { SomeRoutingModule} from './some-routing.module';
import { FieldSumPipe } from '../../../shared/pipes/fieldsum.pipe';
// Other imports...

@NgModule({
    imports: [
        CommonModule,
        SomeRoutingModule, // other imports removed for brevity
    ],
    declarations: [
        FieldSumPipe,
        SomeComponent,
    ],
    exports: [
        FieldSumPipe
    ]
})
export class SomeModule { }