Studio tree for geometric-optics-basics is empty except for phetioEngine

[pixelzoom]

While attempting to test #3, @arouinfar ran into problems. That began a series of comments that are not related to that issue. So I'm moving those comments here.

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@arouinfar said:

@pixelzoom did you forget to push to master? I've pulled all and cleared the cache, but the Studio tree for geometric-optics-basics is empty except for phetioEngine.

@samreid said:

This may be due to a phet-io problem. I'm seeing that the simStarted event is not processing properly, so there is an error in the console. Probably not a geometric-optics-specific problem. Tagging @zepumph in case he has ideas.

Specifically, the simStarted event is going nowhere because phet.phetio.dataStream is coming up falsy in the guard.

@arouinfar said:

Thanks @samreid looks like it is indeed a general problem. I tried a few other sims and they're all showing the same empty tree.

@samreid said:

Thanks, I moved it to a side issue. (EDIT: see https://github.com/phetsims/phet-io/issues/1845)

@samreid said:

OK I pushed a fix in the issue. @arouinfar can you please pull and test?

[zepumph]

Since https://github.com/phetsims/phet-io/issues/1845 is closed, most like this can be also.

[arouinfar]

The tree is no longer empty in master, closing.