common/proxy.scm (send-request): Catch system errors.
Implement proxy debugging.

* lazycat-daemon/lazycatd.scm (initialize): Implement proxy
  debugging.
* lazycat-daemon/proxy-list.scm (proxy-list-load): Likewise.
lazycatd.scm (periodical-ping): Add the check if a message is #f.

* lazycat-daemon/lazycatd.scm (periodical-ping): Add message check to
  prevent calling message-error? method on #f.