Revert "Change StagingErrors to use default instead of generic"

This reverts commit 1a0d4d1916bf8c0a128086fe3619cacb56c668c2.
Revert "Move error messages into english i18n yml file."

This reverts commit a2e6351a746e2275c166422117b492abecb6d9ed.
Revert "Merge remote-tracking branch 'origin/pr/17' into HEAD"

This reverts commit bfcf955c520797218df3225434c2859f5a527162, reversing
changes made to 0edde8327a3e1ba0a6fe2f0f7dabf596ae2122d4.