Introduce OpenAPI specs (#4351)

* wip

* wip

* wip

* Update index.ts

* Update gen-openapi-spec.ts

* Update api.ja-JP.md

* Fix

* Improve doc

* Update gen-openapi-spec.ts

* Update redoc.html

* Improve doc

* Update gen-openapi-spec.ts

* Improve doc

* Update CHANGELOG.md

src/server/api/error.ts

@@ -3,14 +3,16 @@ export class ApiError extends Error {
 	public code: string;
 	public id: string;
 	public kind: string;
+	public httpStatusCode?: number;
 	public info?: any;
 
-	constructor(e?: { message: string, code: string, id: string, kind?: 'client' | 'server' }, info?: any) {
+	constructor(e?: { message: string, code: string, id: string, kind?: 'client' | 'server', httpStatusCode?: number }, info?: any) {
 		if (e == null) e = {
 			message: 'Internal error occurred. Please contact us if the error persists.',
 			code: 'INTERNAL_ERROR',
 			id: '5d37dbcb-891e-41ca-a3d6-e690c97775ac',
-			kind: 'server'
+			kind: 'server',
+			httpStatusCode: 500
 		};
 
 		super(e.message);
@@ -18,6 +20,7 @@ export class ApiError extends Error {
 		this.code = e.code;
 		this.id = e.id;
 		this.kind = e.kind || 'client';
+		this.httpStatusCode = e.httpStatusCode;
 		this.info = info;
 	}
 }