[chore] Apply schema for OpenAPI errors (#4511)

Adds an error struct to Swagger covering normal and OAuth errors for client API endpoints. Now clients using Swagger codegen can handle errors.

Specifically, if you _don't_ have typed errors in your Swagger IDL and you're using `go-swagger` to generate your API client, the error message is discarded and you are only told the status code. With this change in place, clients like `slurp` can tell the user that they tried to upload an emoji that was too big or whatever.

Reviewed-on: https://codeberg.org/superseriousbusiness/gotosocial/pulls/4511
Reviewed-by: tobi <kipvandenbos@noreply.codeberg.org>
Co-authored-by: Vyr Cossont <vyr@noreply.codeberg.org>
Co-committed-by: Vyr Cossont <vyr@noreply.codeberg.org>

2 files changed, 33 insertions, 1 deletions

diff --git a/internal/api/model/application.go b/internal/api/model/application.go
index 3f974683f..e43c2edb3 100644
--- a/internal/api/model/application.go
+++ b/internal/api/model/application.go
@@ -37,7 +37,7 @@ type Application struct {
 	// example: https://example.org/callback?some=query
 	RedirectURI string `json:"redirect_uri,omitempty"`
 	// Post-authorization redirect URIs for the application (OAuth2).
-	// example: [https://example.org/callback?some=query]
+	// example: ["https://example.org/callback?some=query"]
 	RedirectURIs []string `json:"redirect_uris,omitempty"`
 	// Client ID associated with this application.
 	ClientID string `json:"client_id,omitempty"`
diff --git a/internal/api/model/error.go b/internal/api/model/error.go
new file mode 100644
index 000000000..6ec073790
--- /dev/null
+++ b/internal/api/model/error.go
@@ -0,0 +1,32 @@
+// GoToSocial
+// Copyright (C) GoToSocial Authors admin@gotosocial.org
+// SPDX-License-Identifier: AGPL-3.0-or-later
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package model
+
+// Error is a generic public-facing API error.
+//
+// swagger:model error
+type Error struct {
+	// Error is usually a human-readable description of the error.
+	//
+	// For OAuth-related errors, it will be one of the codes listed in
+	// <https://datatracker.ietf.org/doc/html/rfc6749#section-5.2>.
+	Error string `json:"error"`
+
+	// ErrorDescription is only used for OAuth errors, and is a human-readable description of the error.
+	ErrorDescription string `json:"error_description,omitempty"`
+}