Fix pipenet insertion NPE caused by isFaceBlocked

[MCTian-mi]

What

Some machines (like RFTools storage scanner) would get the itemNetHandler with the facing null, and throw a NPE when trying to insert things due to isFaceBlocked calling EnumFacing#getIndex()

This would also fix the same potential crash for fluid pipenets

[Zorbatron]

This probably would've been caught much earlier if at all, if we used more static analysis annotations. I'm planning to go through and spam a whole bunch of @NotNull and @nullable at some point (and general formatting fixes) so hopefully we won't get jumpscared by nulls ever again :clueless:

[Zorbatron]

Sorry for the pings NotNull and nullable