Potential regression by a commit c0159aa in causing `TestAssociation_Shutdown` to fail

[enobufs]

    @enobufs Just wondering: could it be that this PR (commit c0159aa2d49c240362038edf88baa8a9e6cfcede) introduced a regression which makes the unit-test `TestAssociation_Shutdown` fail?

See https://github.com/pion/sctp/actions/runs/3495811764/jobs/5852996166

Originally posted by @stv0g in #239 (comment)

[enobufs]

Hi @jerry-tao, @stv0g, are you able to repro this in your environment? The error does not happen to me... :(

[jerry-tao]

I did not reproduce it either, will dig deeper this week.

[stv0g]

I just tested it again on the current master branch and the test succeeded.

But I see a possibly related PR #236

[stv0g]

I tried to produce it again without success.

So maybe I've dreamt it...

[edaniels]

I just saw it again but only on 1.18