JavaScript and Go backend: Incorrect map cardinality

[khemichew]

Dafny version

4.6.0

Code to produce this issue

method Main() {
 print | map c : char | c in "oxasa" :: c := false |;
}

Command to run and resulting output

Output (for JavaScript and Go): 5
Output (for Python and C#): 4

What happened?

The output for the above should be 4 due to the duplication of 2 'a's of the map keyset; this example has been tested against the nightly version.

What type of operating system are you experiencing the problem on?

Linux

[stefan-aws]

I can confirm the problem. Related: #5557.