refactor: share the PRECHECK type at the top level

server.ts

@@ -56,6 +56,12 @@ export const DEFAULT_SERVER_OPTIONS: SERVER_OPTIONS = {
 	logging: true
 };
 
+/** A `PRECHECK` must take a `Request` and `meta` data and return a `Response` IF THERE IS A PROBLEM. */
+export type PRECHECK = (
+	request: Request,
+	meta: Record<string, any>
+) => undefined | Response | Promise<undefined | Response>;
+
 /**
  * @method LOG_REQUEST Default request logger.
  *