fix(encryption): autoEncryption must error on mongodb < 4.2

Fixes NODE-2334

Author: daprahamian

lib/core/wireprotocol/command.js

@@ -9,6 +9,7 @@ const databaseNamespace = require('./shared').databaseNamespace;
 const isTransactionCommand = require('../transactions').isTransactionCommand;
 const applySession = require('../sessions').applySession;
 const MongoNetworkError = require('../error').MongoNetworkError;
+const maxWireVersion = require('../utils').maxWireVersion;
 
 function isClientEncryptionEnabled(server) {
   return server.autoEncrypter;
@@ -27,6 +28,12 @@ function command(server, ns, cmd, options, callback) {
     return;
   }
 
+  const wireVersion = maxWireVersion(server);
+  if (typeof wireVersion !== 'number' || wireVersion < 8) {
+    callback(new MongoError('Auto-encryption requires a minimum MongoDB version of 4.2'));
+    return;
+  }
+
   _cryptCommand(server, ns, cmd, options, callback);
 }