SessionError: A session has already been opened

[MarkusPint]

if (!VoxeetSDK.session.isOpen()) { await VoxeetSDK.session.open({ name: 'testname', externalId: 1 }); }

Intermittently this code is producing an error: "SessionError: A session has already been opened"

How can this be possible? We've taken care to check that a session is not open before we try to open one, but still it sometimes throws this error.