x/website: running code in go.dev/tour doesn't work

[leitzler]

What did you do?

Opened up https://go.dev/tour/welcome/1 and clicked the "Run" button in the embedded playground.

Browser: Chrome Version 96.0.4664.55 (Official Build) (x86_64)

What did you expect to see?

Output populated.

What did you see instead?

Error communicating with remote server in the output.

The POST request initated when pressing "Run" goes to https://go.dev/_/compile?backend=undefined and it throws an 500 Internal Server Error.

Looks like an side effect from CL 366056 where support for backends was added to the ordinary playground, while the tour doesn't have that option? If I remove undefined from the call it works as expected.

//cc @rsc

[gopherbot]

Change https://golang.org/cl/368914 mentions this issue: _content/js: fix tour playground

[fzipp]

The "Try Go" code box on the go.dev front page has the same problem.

[mknyszek]

CC @dmitshur @rsc

[mknyszek]

Ah, sorry. @jba already got to it. Please ignore, Dmitri, Russ.

[jba]

For the record, it was @jamalc.

[mknyszek]

Ah! My bad. I had only looked at the reviewer and nothing else on that page. Thanks.