fix(server): add type to Plugin so that MiddlewareHandler is typed correctly

[deer]

closes #1531

So the user's code goes from:

export function getLoggerHandler(logSender?: RemoteLogSenderFunction): Plugin {
  const handler: MiddlewareHandler<Logger> = async function (
    _req: Request,
    ctx: MiddlewareHandlerContext<Logger>
  ) {
    ctx.state.logger = new LogModule(logSender);
    return await ctx.next();
  };

  return {
    name: "loggerPlugin",
    middlewares: [
      {
        middleware: {
          handler: handler as MiddlewareHandler<Record<"logger", unknown>>,
        },
        path: "/",
      },
    ],
  };
}

to

export function getLoggerHandler(logSender?: RemoteLogSenderFunction): Plugin<Logger> {
  const handler: MiddlewareHandler<Logger> = async function (
    _req: Request,
    ctx: MiddlewareHandlerContext<Logger>
  ) {
    ctx.state.logger = new LogModule(logSender);
    return await ctx.next();
  };

  return {
    name: "loggerPlugin",
    middlewares: [
      {
        middleware: {
          handler: handler,
        },
        path: "/",
      },
    ],
  };
}

Thoughts?

[deer]

Hmmm, the test plugin should probably also use this...

[marvinhagemeister]

Nice 👍