Update to AVA v6

[razor-x]

Based on #50

I cannot figure out what is the issue with the test failure. However I have seen this before trying to update this to AVA v6 (still stuck on v5): https://github.com/seamapi/javascript-http

[seambot]

Bundle dist size: 6.9M

[razor-x]

@codetheweb Just want to see if you have any ideas here given how much you have worked with AVA. This is the first time I've reproduced the same error in two repos, so maybe we can learn something new: seamapi/javascript-http#65

[codetheweb]

Does seamapi/javascript-http use shared workers? I remember seeing this error before in edgespec, but I thought it was my fault at the time.

[razor-x]

@codetheweb It starts and uses the fake, but I'm not sure if that means it uses shared workers or not.

[codetheweb]

I think it's an internal AVA bug with t.throwsAsync()? I think? Pretty sure it's a result of the Axios error not serializing properly.

e.g. when run outside t.throwsAsync() it works fine, and if you try/catch t.throwsAsync() you can see the internal AVA error

[stale]

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