Remove inflection from missing controller errors.

When the errors have inflection, it makes the error messages pretty
misleading, as we tell the developer to do a thing they might have
already done.
Simplify Table::get() test.

There is not much value in using mocks when getting an actual error is
much simpler.
Fix warnings in Table::get()

Avoid array_combine errors by checking argument counts before calling
array combine.
Use early return in Table::get().
Remove unused import.