Extend http interceptor to normalize errors

frontend/src/app/services/http-cache.interceptor.ts

@@ -1,7 +1,7 @@
 import { Inject, Injectable, PLATFORM_ID } from '@angular/core';
-import { HttpInterceptor, HttpEvent, HttpRequest, HttpHandler, HttpResponse, HttpHeaders } from '@angular/common/http';
+import { HttpInterceptor, HttpEvent, HttpRequest, HttpHandler, HttpResponse, HttpErrorResponse, HttpHeaders } from '@angular/common/http';
 import { Observable, of } from 'rxjs';
-import { tap } from 'rxjs/operators';
+import { catchError, tap } from 'rxjs/operators';
 import { TransferState, makeStateKey } from '@angular/platform-browser';
 import { isPlatformBrowser } from '@angular/common';
 
@@ -36,7 +36,8 @@ export class HttpCacheInterceptor implements HttpInterceptor {
     }
 
     return next.handle(request)
-      .pipe(tap((event: HttpEvent<any>) => {
+      .pipe(
+        tap((event: HttpEvent<any>) => {
           if (!this.isBrowser && event instanceof HttpResponse) {
             let keyId = request.url.split('/').slice(3).join('/');
             const headers = {};
@@ -45,6 +46,31 @@ export class HttpCacheInterceptor implements HttpInterceptor {
             }
             this.transferState.set<any>(makeStateKey('/' + keyId), { response: event, headers });
           }
-      }));
+        }),
+        catchError((e) => {
+          if (e instanceof HttpErrorResponse) {
+            if (e.status === 0) {
+              throw new HttpErrorResponse({
+                error: 'Unknown error',
+                headers: e.headers,
+                status: 0,
+                statusText: 'Unknown error',
+                url: e.url,
+              });
+            } else {
+              throw e;
+            }
+          } else {
+            const msg = e?.['message'] || 'Unknown error';
+            throw new HttpErrorResponse({
+              error: msg,
+              headers: new HttpHeaders(),
+              status: 0,
+              statusText: msg,
+              url: '',
+            });
+          }
+        })
+      );
   }
 }