fix: auto encrypter client options

Author: durran

src/client-side-encryption/auto_encrypter.ts

@@ -239,8 +239,6 @@ export class AutoEncrypter {
     this._proxyOptions = options.proxyOptions || {};
     this._tlsOptions = options.tlsOptions || {};
     this._kmsProviders = options.kmsProviders || {};
-    this._awsCredentialProvider =
-      client.options.credentials?.mechanismProperties.AWS_CREDENTIAL_PROVIDER;
 
     const mongoCryptOptions: MongoCryptOptions = {
       cryptoCallbacks
@@ -331,6 +329,11 @@ export class AutoEncrypter {
    * This function is a no-op when bypassSpawn is set or the crypt shared library is used.
    */
   async init(): Promise<MongoClient | void> {
+    // This is handled during init() as the auto encrypter is instantiated during the client's
+    // parseOptions() call, so the client doesn't have its options set at that point.
+    this._awsCredentialProvider =
+      this._client.options.credentials?.mechanismProperties.AWS_CREDENTIAL_PROVIDER;
+
     if (this._bypassMongocryptdAndCryptShared || this.cryptSharedLibVersionInfo) {
       return;
     }