Only generate and attach correlationId if apm is present

Saves both the UUID computation and transport bytes for the id if we're
not going to use it in the end.

lib/raygun.ts

@@ -34,8 +34,10 @@ import { v4 as uuidv4 } from "uuid";
 
 const debug = require("debug")("raygun");
 
-
-let apmBridge: undefined | null | {notify(e: string | Error, s: string): void} = undefined;
+let apmBridge:
+  | undefined
+  | null
+  | { notify(e: string | Error, s: string): void } = undefined;
 
 try {
   if (module.parent) {
@@ -222,12 +224,6 @@ class Raygun {
     request?: Request,
     tags?: Tag[]
   ): Message {
-    const correlationId = uuidv4();
-
-    if (apmBridge) {
-      apmBridge.notify(exception, correlationId);
-    }
-
     let mergedTags: Tag[] = [];
 
     if (this._tags) {
@@ -269,7 +265,13 @@ class Raygun {
           : message;
     }
 
-    message.details.correlationId = correlationId;
+    if (apmBridge) {
+      const correlationId = uuidv4();
+
+      apmBridge.notify(exception, correlationId);
+
+      message.details.correlationId = correlationId;
+    }
 
     if (this._isOffline) {
       this.offlineStorage().save(JSON.stringify(message), callback || emptyCallback);