A couple of fixes to CatchableFatalErrorException

Followup to https://gerrit.wikimedia.org/r/#/c/140414/, a couple
of issues were not spotted during the merge

Change-Id: Ia6543845f1ec851c0b0ae53eb9bc021c27c34fff
Simplify Flow colors to use from core

Use from core when they exist there.

Dependency: I68cd4de1df515cf059a1d9e45cd3ff801a0a1c84
Change-Id: I519beb8b0ffae0bef387cefa5026ee94282001df
Merge "A couple of fixes to CatchableFatalErrorException"
Merge "Simplify Flow colors to use from core"