Do not use default

src/metrics.ts

@@ -15,7 +15,7 @@ limitations under the License.
 */
 /* eslint-disable max-classes-per-file, @typescript-eslint/no-empty-function */
 
-import { Gauge, Counter, Histogram, default as promClient } from "prom-client";
+import { Gauge, Counter, Histogram, collectDefaultMetrics, register } from "prom-client";
 import { Log } from "./log";
 import { Appservice,
     IMetricContext,
@@ -69,15 +69,16 @@ export class PrometheusBridgeMetrics implements IBridgeMetrics {
     private httpServer: http.Server;
 
     public init(as: Appservice, config: DiscordBridgeConfigMetrics) {
-        promClient.collectDefaultMetrics();
+        collectDefaultMetrics();
         // TODO: Bind this for every user.
         this.httpServer = http.createServer((req, res) => {
             if (req.method !== "GET" || req.url !== "/metrics") {
                 res.writeHead(404, "Not found");
                 res.end();
+                return;
             }
-            res.writeHead(200, "OK", {"Content-Type": promClient.register.contentType});
-            res.write(promClient.register.metrics());
+            res.writeHead(200, "OK", {"Content-Type": register.contentType});
+            res.write(register.metrics());
             res.end();
         });
         this.matrixCallCounter = new Counter({
@@ -85,41 +86,41 @@ export class PrometheusBridgeMetrics implements IBridgeMetrics {
             labelNames: ["method", "result"],
             name: "matrix_api_calls",
         });
-        promClient.register.registerMetric(this.matrixCallCounter);
+        register.registerMetric(this.matrixCallCounter);
 
         this.remoteCallCounter = new Counter({
             help: "Count of remote API calls made",
             labelNames: ["method"],
             name: "remote_api_calls",
         });
-        promClient.register.registerMetric(this.remoteCallCounter);
+        register.registerMetric(this.remoteCallCounter);
 
         this.storeCallCounter = new Counter({
             help: "Count of store function calls made",
             labelNames: ["method", "cached"],
             name: "store_calls",
         });
-        promClient.register.registerMetric(this.storeCallCounter);
+        register.registerMetric(this.storeCallCounter);
 
         this.presenceGauge = new Gauge({
             help: "Count of users in the presence queue",
             name: "active_presence_users",
         });
-        promClient.register.registerMetric(this.presenceGauge);
+        register.registerMetric(this.presenceGauge);
 
         this.matrixRequest = new Histogram({
             help: "Histogram of processing durations of received Matrix messages",
             labelNames: ["outcome"],
             name: "matrix_request_seconds",
         });
-        promClient.register.registerMetric(this.matrixRequest);
+        register.registerMetric(this.matrixRequest);
 
         this.remoteRequest = new Histogram({
             help: "Histogram of processing durations of received remote messages",
             labelNames: ["outcome"],
             name: "remote_request_seconds",
         });
-        promClient.register.registerMetric(this.remoteRequest);
+        register.registerMetric(this.remoteRequest);
 
         this.requestsInFlight = new Map();
         setInterval(() => {