Describe the bug
We received more than 100 warning logs today where it is impossible to detect the actual root cause for the error: ["2022-11-09T03:40:00.141Z"] Received I/O error ([object Object]) for streaming request - will retry.

Looks like in https://github.com/launchdarkly/node-server-sdk/blob/main/messages.js#L10 the error object is not properly stringified.

To reproduce
It is hard to reproduce on our side but it should be possible by calling httpErrorMessage with an error object not containing a message.

Expected behavior
The actual error is properly logged to the warning message.

Logs
["2022-11-09T03:40:00.141Z"] Received I/O error ([object Object]) for streaming request - will retry

SDK version
6.4.3

Language version, developer tools
node v16.14.2

OS/platform
Docker node16 image