fix(NODE-4425): webpack optional import of FLE issue

src/encrypter.ts

@@ -6,7 +6,7 @@ import { MongoInvalidArgumentError, MongoMissingDependencyError } from './error'
 import { MongoClient, MongoClientOptions } from './mongo_client';
 import { Callback, getMongoDBClientEncryption } from './utils';
 
-let AutoEncrypterClass: AutoEncrypter;
+let AutoEncrypterClass: { new (...args: ConstructorParameters<AutoEncrypter>): AutoEncrypter };
 
 /** @internal */
 const kInternalClient = Symbol('internalClient');
@@ -123,15 +123,13 @@ export class Encrypter {
   }
 
   static checkForMongoCrypt(): void {
-    try {
-      // NOTE(NODE-3199): Ensure you always wrap an optional require in the try block
-      const mongodbClientEncryption = getMongoDBClientEncryption();
-      AutoEncrypterClass = mongodbClientEncryption.extension(require('../lib/index')).AutoEncrypter;
-    } catch {
+    const mongodbClientEncryption = getMongoDBClientEncryption();
+    if (mongodbClientEncryption == null) {
       throw new MongoMissingDependencyError(
         'Auto-encryption requested, but the module is not installed. ' +
           'Please add `mongodb-client-encryption` as a dependency of your project'
       );
     }
+    AutoEncrypterClass = mongodbClientEncryption.extension(require('../lib/index')).AutoEncrypter;
   }
 }

src/utils.ts

@@ -12,6 +12,7 @@ import { LEGACY_HELLO_COMMAND } from './constants';
 import type { AbstractCursor } from './cursor/abstract_cursor';
 import type { FindCursor } from './cursor/find_cursor';
 import type { Db } from './db';
+import type { AutoEncrypter } from './deps';
 import {
   AnyError,
   MongoCompatibilityError,
@@ -1409,24 +1410,34 @@ export function commandSupportsReadConcern(command: Document, options?: Document
   return false;
 }
 
-/**
- * A utility function to get the instance of mongodb-client-encryption, if it exists.
- *
- * @throws MongoMissingDependencyError if mongodb-client-encryption isn't installed.
- * @returns
- */
-export function getMongoDBClientEncryption() {
-  let mongodbClientEncryption;
+/** A utility function to get the instance of mongodb-client-encryption, if it exists. */
+export function getMongoDBClientEncryption(): {
+  extension: (mdb: typeof import('../src/index')) => {
+    AutoEncrypter: any;
+    ClientEncryption: any;
+  };
+} | null {
+  let mongodbClientEncryption = null;
 
   // NOTE(NODE-4254): This is to get around the circular dependency between
   // mongodb-client-encryption and the driver in the test scenarios.
   if (
     typeof process.env.MONGODB_CLIENT_ENCRYPTION_OVERRIDE === 'string' &&
     process.env.MONGODB_CLIENT_ENCRYPTION_OVERRIDE.length > 0
   ) {
-    mongodbClientEncryption = require(process.env.MONGODB_CLIENT_ENCRYPTION_OVERRIDE);
+    try {
+      // NOTE(NODE-3199): Ensure you always wrap an optional require in the try block
+      mongodbClientEncryption = require(process.env.MONGODB_CLIENT_ENCRYPTION_OVERRIDE);
+    } catch {
+      // ignore
+    }
   } else {
-    mongodbClientEncryption = require('mongodb-client-encryption');
+    try {
+      // NOTE(NODE-3199): Ensure you always wrap an optional require in the try block
+      mongodbClientEncryption = require('mongodb-client-encryption');
+    } catch {
+      // ignore
+    }
   }
 
   return mongodbClientEncryption;

test/tools/unified-spec-runner/unified-utils.ts

@@ -206,6 +206,11 @@ export function makeConnectionString(
 export function getClientEncryptionClass(): ClientEncryption {
   try {
     const mongodbClientEncryption = getMongoDBClientEncryption();
+    if (mongodbClientEncryption == null) {
+      throw new MongoMissingDependencyError(
+        'Attempting to import mongodb-client-encryption but it is not installed.'
+      );
+    }
 
     // eslint-disable-next-line @typescript-eslint/no-var-requires
     const { ClientEncryption } = mongodbClientEncryption.extension(require('../../../src/index'));