Revert "chore: move logic out of monitoring check"

This reverts commit c670bda.

src/cmap/connection.ts

@@ -374,24 +374,23 @@ export class Connection extends TypedEventEmitter<ConnectionEvents> {
     this.emit('message', message);
     let operationDescription = this[kQueue].get(message.responseTo);
 
-    // Protect against multiplexing.
-    if (this[kQueue].size > 1) {
-      this.onError(new MongoRuntimeError(INVALID_QUEUE_SIZE));
-      return;
-    }
-
     if (!operationDescription && this.isMonitoringConnection) {
       // This is how we recover when the initial hello's requestId is not
       // the responseTo when hello responses have been skipped:
 
-      // Get the first orphaned operation description.
-      const entry = this[kQueue].entries().next();
-      if (entry) {
-        const [requestId, orphaned]: [number, OperationDescription] = entry.value;
-        // If the orphaned operation description exists then set it.
-        operationDescription = orphaned;
-        // Remove the entry with the bad request id from the queue.
-        this[kQueue].delete(requestId);
+      // First check if the map is of invalid size
+      if (this[kQueue].size > 1) {
+        this.onError(new MongoRuntimeError(INVALID_QUEUE_SIZE));
+      } else {
+        // Get the first orphaned operation description.
+        const entry = this[kQueue].entries().next();
+        if (entry) {
+          const [requestId, orphaned]: [number, OperationDescription] = entry.value;
+          // If the orphaned operation description exists then set it.
+          operationDescription = orphaned;
+          // Remove the entry with the bad request id from the queue.
+          this[kQueue].delete(requestId);
+        }
       }
     }