### Background
#1102 changed how `Interpreter.Use` interprets export paths such that the last path component is stripped and used as the package name. This resulted in #1139 - attempting to Use an export with only one path component, such as `foo`, would result in the import path being `.`.
### Breaking API Change
This PR changes the signature of `Interpreter.Use` from `Use(Exports)` to `Use(Exports) error`.
### Fix for #1139
With this PR, if Use is called with an incomplete export path, such as `foo`, Use will return an error.
Eval returns the value of the root node of AST, so ensure
that node values are propagated back to ExprStmt and BlockStmt,
which should be sufficient to handle evaluation of simple
statements.