more strict error type checking in most packages and backend plugins

Signed-off-by: Patrik Oldsberg <poldsberg@gmail.com>

plugins/auth-backend/src/lib/oauth/OAuthAdapter.ts

@@ -22,7 +22,7 @@ import {
   BackstageIdentity,
   AuthProviderConfig,
 } from '../../providers/types';
-import { InputError, NotAllowedError } from '@backstage/errors';
+import { InputError, isError, NotAllowedError } from '@backstage/errors';
 import { TokenIssuer } from '../../identity/types';
 import { readState, verifyNonce } from './helpers';
 import { postMessageResponse, ensuresXRequestedWith } from '../flow';
@@ -153,13 +153,13 @@ export class OAuthAdapter implements AuthProviderRouteHandlers {
         response,
       });
     } catch (error) {
+      const { name, message } = isError(error)
+        ? error
+        : new Error('Encountered invalid error'); // Being a bit safe and not forwarding the bad value
       // post error message back to popup if failure
       return postMessageResponse(res, appOrigin, {
         type: 'authorization_response',
-        error: {
-          name: error.name,
-          message: error.message,
-        },
+        error: { name, message },
       });
     }
   }
@@ -220,7 +220,7 @@ export class OAuthAdapter implements AuthProviderRouteHandlers {
 
       res.status(200).json(response);
     } catch (error) {
-      res.status(401).send(`${error.message}`);
+      res.status(401).send(String(error));
     }
   }
 

plugins/auth-backend/src/providers/saml/provider.ts

@@ -29,6 +29,7 @@ import {
 import { AuthProviderRouteHandlers, AuthProviderFactory } from '../types';
 import { postMessageResponse } from '../../lib/flow';
 import { TokenIssuer } from '../../identity/types';
+import { isError } from '@backstage/errors';
 
 type SamlInfo = {
   fullProfile: any;
@@ -93,12 +94,12 @@ export class SamlAuthProvider implements AuthProviderRouteHandlers {
         },
       });
     } catch (error) {
+      const { name, message } = isError(error)
+        ? error
+        : new Error('Encountered invalid error'); // Being a bit safe and not forwarding the bad value
       return postMessageResponse(res, this.appUrl, {
         type: 'authorization_response',
-        error: {
-          name: error.name,
-          message: error.message,
-        },
+        error: { name, message },
       });
     }
   }

plugins/auth-backend/src/service/router.ts

@@ -26,7 +26,7 @@ import {
   PluginDatabaseManager,
   PluginEndpointDiscovery,
 } from '@backstage/backend-common';
-import { NotFoundError } from '@backstage/errors';
+import { assertError, NotFoundError } from '@backstage/errors';
 import { CatalogClient } from '@backstage/catalog-client';
 import { Config } from '@backstage/config';
 import { createOidcRouter, DatabaseKeyStore, TokenFactory } from '../identity';
@@ -121,6 +121,7 @@ export async function createRouter({
 
         router.use(`/${providerId}`, r);
       } catch (e) {
+        assertError(e);
         if (process.env.NODE_ENV !== 'development') {
           throw new Error(
             `Failed to initialize ${providerId} auth provider, ${e.message}`,