refactor: code improvements, bugfixing

src/app/material.module.ts

@@ -4,8 +4,10 @@ import { MatCardModule } from '@angular/material/card';
 import { MatIconModule } from '@angular/material/icon';
 import { MatInputModule } from '@angular/material/input';
 import { MatListModule } from '@angular/material/list';
+import { MatProgressBarModule } from '@angular/material/progress-bar';
 import { MatSidenavModule } from '@angular/material/sidenav';
 import { MatToolbarModule } from '@angular/material/toolbar';
+import { MatSnackBarModule } from '@angular/material/snack-bar';
 
 @NgModule({
     exports: [
@@ -14,7 +16,9 @@ import { MatToolbarModule } from '@angular/material/toolbar';
         MatIconModule,
         MatInputModule,
         MatListModule,
+        MatProgressBarModule,
         MatSidenavModule,
+        MatSnackBarModule,
         MatToolbarModule,
     ],
 })