refs: TryGhost/Toolbox#147
* Replaces all references to isIgnitionError with isGhostError
* Switches use of GhostError to InternalServerError - as GhostError is no longer public
There are places where InternalServerError is not the valid error, and new errors should be added to the @tryghost/errors package to ensure that we can use semantically correct errors in those cases.
refs https://github.com/TryGhost/Team/issues/1178
The "up" migration that this util generates correctly throws if the
pre-requisite data cannot be found in the database. The "down" migration
however was incorrectly mirroring this behaviour of throwing - which
meant that it wasn't idempotent, as it does not require a permission or
role to existing if it wants to move relations between them.
- this is a small part of a bit of cleanup of our test files
- the goal is to make the existing tests clearer with a view to making it easier to write more tests
- this makes the test structure follow the codebase structure more closely
- eventually we will colocate the tests as we break the codebase down further
