fix: guard global.metrics in singleFlightMiddleware

src/HttpClient/middlewares/inflight.ts

@@ -17,10 +17,13 @@
   // cancel any request
   ctx.config.cancelToken = undefined
 
-  if (!metricsAdded) {
+  // global.metrics is only initialized by startApp() in the IO service
+  // runtime. Standalone consumers of HttpClient (e.g. the toolbelt CLI)
+  // run without it, so guard the bare global reference.
+  if (!metricsAdded && typeof metrics !== 'undefined') {
     metrics.addOnFlushMetric(() => ({
       name: 'node-vtex-api-inflight-map-size',
-      size: inflight.entries.length,
+      size: inflight.size,
     }))
     metricsAdded = true
   }
@@ -32,9 +35,9 @@
     const memoized = await inflight.get(key)!
     ctx.inflightHit = isInflight
     ctx.response = memoized.response
     return
   } else {
     const promise = new Promise<Inflight>(async (resolve, reject) => {
       try {
         await next()
         resolve({