stub out export endpoint

mod.ts

@@ -60,6 +60,14 @@ Deno.serve({ port: config.api.port }, async (req) => {
 
         return genericResponse(STATUS_CODE.OK, JSON.stringify(plans));
       } else if (path.startsWith('/export/')) {
+        const userId = path.replace('/list/', '');
+        const userMatch = await dbClient.query('SELECT id FROM users WHERE id = ?', [userId]).catch(() => {
+          failed = true;
+        });
+        if (failed) return genericResponse(STATUS_CODE.InternalServerError, "Couldn't read DB.");
+        if (!userMatch.length) return genericResponse(STATUS_CODE.NotFound, 'User ID does not exist.');
+
+        // WIP: export plans to zip code goes here
         return genericResponse(STATUS_CODE.NotImplemented, 'WIP');
       }
     } else if (req.method === 'POST' && path === '/enroll') {