Corrected NativeLibraryWrapperService.

src/app/native-library-wrapper.service.ts

@@ -0,0 +1,37 @@
+import {Injectable} from '@angular/core';
+import * as NativePunycode from 'punycode';
+import * as NativeQuotedPrintable from 'quoted-printable';
+import * as NativeUtf8 from 'utf8';
+
+@Injectable({
+  providedIn: 'root'
+})
+export class NativeLibraryWrapperService {
+  public utf8: Utf8;
+  public quotedPrintable: QuotedPrintable;
+  public punycode: Punycode;
+
+  constructor() {
+    this.utf8 = NativeUtf8;
+    this.quotedPrintable = NativeQuotedPrintable;
+    this.punycode = NativePunycode;
+  }
+}
+
+interface Punycode {
+  encode(input: string): string;
+
+  decode(input: string): string;
+}
+
+interface QuotedPrintable {
+  encode(input: string): string;
+
+  decode(input: string): string;
+}
+
+interface Utf8 {
+  encode(input: any): string;
+
+  decode(input: string): any;
+}