Env Viz: Import statements handled inconsistently

[martin-henz]

Example:
https://share.sourceacademy.org/bqb59

The step above makes sense: import declarations are hoisted to the beginning.

Why is there a POP after the first import, but not after the second?

This step and the next steps are not leading to any change.

But now suddenly:

Stepping back from the last step shows states that are inconsistent with the forward steps.