feat: Use an ErrorHandler to generate JSON errors

Author: joachimvh

packages/uma/config/default.json

@@ -58,29 +58,25 @@
       "errorHandler": { "@id": "urn:uma:default:ErrorHandler" },
       "responseWriter": { "@id": "urn:uma:default:ResponseWriter" },
       "operationHandler": {
-        "@id": "urn:uma:default:JsonHttpErrorHandler"
+        "@id": "urn:uma:default:HttpHandlerController"
       }
     },
     {
-      "@id": "urn:uma:default:JsonHttpErrorHandler",
-      "@type": "JsonHttpErrorHandler",
-      "nestedHandler": {
-        "@id": "urn:uma:default:HttpHandlerController",
-        "@type": "WaterfallHandler",
-        "handlers": [
-          { "@id": "urn:uma:default:UmaConfigRouteHandler" },
-          { "@id": "urn:uma:default:JwksRouteHandler" },
-          { "@id": "urn:uma:default:TokenRouteHandler" },
-          { "@id": "urn:uma:default:PermissionRegistrationRouteHandler" },
-          { "@id": "urn:uma:default:ResourceRegistrationRouteHandler" },
-          { "@id": "urn:uma:default:ResourceRegistrationOpsRouteHandler" },
-          { "@id": "urn:uma:default:IntrospectionRouteHandler" },
-          {
-            "@type": "StaticThrowHandler",
-            "error": { "@type": "NotFoundHttpError" }
-          }
-        ]
-      }
+      "@id": "urn:uma:default:HttpHandlerController",
+      "@type": "WaterfallHandler",
+      "handlers": [
+        { "@id": "urn:uma:default:UmaConfigRouteHandler" },
+        { "@id": "urn:uma:default:JwksRouteHandler" },
+        { "@id": "urn:uma:default:TokenRouteHandler" },
+        { "@id": "urn:uma:default:PermissionRegistrationRouteHandler" },
+        { "@id": "urn:uma:default:ResourceRegistrationRouteHandler" },
+        { "@id": "urn:uma:default:ResourceRegistrationOpsRouteHandler" },
+        { "@id": "urn:uma:default:IntrospectionRouteHandler" },
+        {
+          "@type": "StaticThrowHandler",
+          "error": { "@type": "NotFoundHttpError" }
+        }
+      ]
     },
     {
       "comment": "Configuration for the UMA AS."

packages/uma/config/http/parsing/components/error-handler.json

@@ -1,15 +1,23 @@
 {
-  "@context": "https://linkedsoftwaredependencies.org/bundles/npm/@solid/community-server/^7.0.0/components/context.jsonld",
+  "@context": [
+    "https://linkedsoftwaredependencies.org/bundles/npm/@solidlab/uma/^0.0.0/components/context.jsonld",
+    "https://linkedsoftwaredependencies.org/bundles/npm/@solid/community-server/^7.0.0/components/context.jsonld"
+  ],
   "@graph": [
     {
-      "comment": "Wraps around the main error handler as a fallback in case something goes wrong.",
       "@id": "urn:uma:default:ErrorHandler",
-      "@type": "SafeErrorHandler",
-      "errorHandler": {
-        "comment": "Redirects are created internally by throwing a specific error; this handler converts them to the correct response.",
-        "@id": "urn:uma:default:RedirectingErrorHandler",
-        "@type": "RedirectingErrorHandler"
-      }
+      "@type": "WaterfallHandler",
+      "handlers": [
+        {
+          "comment": "Redirects are created internally by throwing a specific error; this handler converts them to the correct response.",
+          "@id": "urn:uma:default:RedirectingErrorHandler",
+          "@type": "RedirectingErrorHandler"
+        },
+        {
+          "@id": "urn:uma:default:JsonErrorHandler",
+          "@type": "JsonErrorHandler"
+        }
+      ]
     }
   ]
 }

packages/uma/src/index.ts

@@ -59,5 +59,5 @@ export * from './util/ReType';
 
 // HTTP
 export * from './util/http/identifier/BaseTargetExtractor';
-export * from './util/http/server/ErrorHandler';
 export * from './util/http/server/InteractionRouterHandler';
+export * from './util/http/server/JsonErrorHandler';

packages/uma/src/util/http/server/ErrorHandler.ts

@@ -0,0 +1,35 @@
+import {
+  APPLICATION_JSON,
+  CONTENT_TYPE,
+  ErrorHandler,
+  ErrorHandlerArgs,
+  getLoggerFor,
+  guardedStreamFrom,
+  RepresentationMetadata,
+  ResponseDescription
+} from '@solid/community-server';
+
+/**
+ * {@link ErrorHandler} that returns a JSON representation of the error.
+ */
+export class JsonErrorHandler extends ErrorHandler {
+  protected readonly logger = getLoggerFor(this);
+
+  public constructor(protected readonly showStackTrace = false) {
+    super();
+  }
+
+  public async handle({ request, error }: ErrorHandlerArgs): Promise<ResponseDescription> {
+    this.logger.error(`Returned error for ${request.method} '${request.url}': ${error.name} ${error.message}`);
+
+    return new ResponseDescription(
+      error.statusCode,
+      new RepresentationMetadata({[CONTENT_TYPE]: APPLICATION_JSON}),
+      guardedStreamFrom(JSON.stringify({
+        status: error.statusCode,
+        error: error.name,
+        message: error.message,
+        ...(this.showStackTrace && error.stack ? { stack: error.stack } : {})
+      })));
+  }
+}