Updated to angular 11

Now compiling with strict mode in typescript
Need to error checking now

bookie/src/app/printers/printer.service.ts

@@ -18,7 +18,7 @@ const serviceName = 'PrinterService';
 export class PrinterService {
   constructor(private http: HttpClient, private log: ErrorLoggerService) {}
 
-  get(id: string): Observable<Printer> {
+  get(id: string | null): Observable<Printer> {
     const getUrl: string = id === null ? url : `${url}/${id}`;
     return <Observable<Printer>>(
       this.http