Added request error handling to notification flush

[pistachiobaby]

During our Internal GREAT FLAKE SHAKE we discovered that sometimes the wds child process will attempt to forward notifications to the parent when the parent is not active. This lead to sparse EPIPE errors being thrown.

The underlying issue of the child forwarding requests to the parent exists, but this at least will avoid any crashing due to uncaught exceptions.

[airhorns]

@pistachiobaby did you want to add the same error handling to the other places where we make HTTP requests to the IPC servers?