test: ensure proper error properties in tests

Author: nbbeeken

test/integration/client-side-encryption/client_side_encryption.prose.10.kms_tls.test.ts

@@ -47,6 +47,8 @@ describe('10. KMS TLS Tests', function () {
       error => error
     );
 
+    expect(error).to.exist;
+    expect(error, error.stack).to.have.property('cause').that.is.instanceOf(Error);
     expect(error.cause.message, error.stack).to.include('certificate has expired');
   });
 
@@ -58,6 +60,8 @@ describe('10. KMS TLS Tests', function () {
       error => error
     );
 
+    expect(error).to.exist;
+    expect(error, error.stack).to.have.property('cause').that.is.instanceOf(Error);
     expect(error.cause.message, error.stack).to.include('does not match certificate');
   });
 });