Dict increment assignment ( dict[key] += 1 ) not working in Transcrypt/Screeps Python

[moreMizzh]

Describe the bug

In the Screeps Python (Transcrypt) environment, increment assignment on a dictionary value does not work as expected.

To Reproduce

Example code:

cs_dict = {"a": 0}
console.log("a: ", cs_dict["a"])
cs_dict["a"] += 1
console.log("a: ", cs_dict["a"])
cs_dict["a"] = 1
console.log("a: ", cs_dict["a"])

Actual behavior

The output is:

a:  0
a:  0
a:  0

Expected behavior

The expected output should be:

a:  0
a:  1
a:  1

Additional context

This issue makes it impossible to use dict[key] += 1 for counting in Screeps Python.
Please help to check if this is a Transcrypt compatibility bug or a Screeps Python integration issue.

Thank you!