*  Renames `crate::resolve::ResolveError` to `crate::resolve::Error`
* Adds type alias `crate::resolve::ResolveError` for `crate::resolve::Error`
* Renames `crate::assign::AssignError` to `crate::assign::Error`
* Adds type alias `crate::assign::AssignError` for crate::assign::Error`
* Adds `position` (token index) to variants of `assign::Error` & `resolve::Error`

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Co-authored-by: André Mello <3285133+asmello@users.noreply.github.com>