[#4] Fix anotations discarded in some instructions

Description

Problem: The cursor jumps a bit oddly around the instructions fixed in morley!727 (merged) when they are wrapped in annotations, and the stack is not properly shown.

Solution: Only yield a snapshot if we just entered its nested annotation instruction (or if there wasn't an annotation in the first place) and have the runInner function set its position before executing the instruction. Also, fix a small issue with MapName found while testing this MR.

This depends on morley!727 (merged).

Related issue(s)

Resolves #4 (closed)

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