fix: only check for transaction state if session exists

Author: mbroadst

lib/operations/execute_operation.js

@@ -126,7 +126,7 @@ function executeWithServerSelection(topology, operation, callback) {
 
     const shouldRetryReads =
       topology.s.options.retryReads !== false &&
-      !operation.session.inTransaction() &&
+      (operation.session && !operation.session.inTransaction()) &&
       maxWireVersion(server) >= 6;
 
     if (operation.hasAspect(Aspect.RETRYABLE) && shouldRetryReads) {