Hey Brian,
Your original post stated that you were getting a PHP Fatal Error and you did not mention the 502 error. 502 errors are usually related to a proxy or load balancer problem … i.e. a communication problem.
Based on the information you are providing, It looks to me like you may have two separate issues:
1) A communication problem (502 error)
2) A faulty plugin (PHP Fatal Error)
Some suggestions:
– Is your WordPress install behind a load balancer or reverse proxy?
– Is this is a hosted WordPress install? If so your provider may be having a problem?
– Are your twitter credentials ok? Twitter also uses load balancers/reverse proxies?
Hope this helps as I know the SwiftIdea guys are likely catching some zzzz’s right now.