fix(NODE-3199): unable to bundle driver due to uncaught require

lib/core/auth/mongodb_aws.js

@@ -9,6 +9,7 @@ const url = require('url');
 
 let aws4;
 try {
+  // Ensure you always wrap an optional require in the try block NODE-3199
   aws4 = require('aws4');
 } catch (e) {
   // don't do anything;

lib/core/auth/scram.js

@@ -11,6 +11,7 @@ const Binary = BSON.Binary;
 
 let saslprep;
 try {
+  // Ensure you always wrap an optional require in the try block NODE-3199
   saslprep = require('saslprep');
 } catch (e) {
   // don't do anything;

lib/core/index.js

@@ -5,6 +5,7 @@ const require_optional = require('optional-require')(require);
 const EJSON = require('./utils').retrieveEJSON();
 
 try {
+  // Ensure you always wrap an optional require in the try block NODE-3199
   // Attempt to grab the native BSON parser
   const BSONNative = require_optional('bson-ext');
   // If we got the native parser, use it instead of the

lib/core/utils.js

@@ -27,6 +27,7 @@ function retrieveKerberos() {
   let kerberos;
 
   try {
+    // Ensure you always wrap an optional require in the try block NODE-3199
     kerberos = requireOptional('kerberos');
   } catch (err) {
     if (err.code === 'MODULE_NOT_FOUND') {

lib/encrypter.js

@@ -3,22 +3,27 @@ const MongoClient = require('./mongo_client');
 const BSON = require('./core/connection/utils').retrieveBSON();
 const MongoError = require('./core/error').MongoError;
 
+let mongodbClientEncryption = undefined;
 try {
-  require.resolve('mongodb-client-encryption');
+  // Ensure you always wrap an optional require in the try block NODE-3199
+  mongodbClientEncryption = require('mongodb-client-encryption');
 } catch (err) {
   throw new MongoError(
     'Auto-encryption requested, but the module is not installed. ' +
       'Please add `mongodb-client-encryption` as a dependency of your project'
   );
 }
 
-const mongodbClientEncryption = require('mongodb-client-encryption');
-if (typeof mongodbClientEncryption.extension !== 'function') {
+if (
+  mongodbClientEncryption === undefined ||
+  typeof mongodbClientEncryption.extension !== 'function'
+) {
   throw new MongoError(
     'loaded version of `mongodb-client-encryption` does not have property `extension`. ' +
       'Please make sure you are loading the correct version of `mongodb-client-encryption`'
   );
 }
+
 const AutoEncrypter = mongodbClientEncryption.extension(require('../index')).AutoEncrypter;
 
 const kInternalClient = Symbol('internalClient');