On every beat do is always one beat behind

[pikurasa]

This can be observed in:

https://github.com/sugarlabs/musicblocks/files/4871015/Improvisation.html.zip

On every beat do starts the action on the second beat, not the first.

On every note do does exactly what I expect, at the right time.

I am a little confused because I know there is discussion of "before" and "after". However, the "on every note do" seems to be putting the action "inside the note value" whereas "on every beat do" is putting the action after the beat has occurred (and abruptly, as if it is outside of the note value clamp).

[pikurasa]

I also got an error the first time I ran the code. It ran well the second time.

These are the errors I get the first time.

synthutils.js:1202 Uncaught TypeError: Cannot use 'in' operator to search for 'piano' in undefined
    at Synth.loadSynth (synthutils.js:1202)
    at Function.setTimbre (ToneActions.js:55)
    at SetTimbreBlock.flow (ToneBlocks.js:620)
    at Logo.runFromBlockNow (logo.js:1597)
    at logo.js:1474
11
turtle-singer.js:1024 Uncaught TypeError: Cannot use 'in' operator to search for 'piano' in undefined
    at Function.processNote (turtle-singer.js:1024)
    at __listener (RhythmActions.js:138)
    at a.b._dispatchEvent (VM452 easeljs.min.js:12)
    at a.b._dispatchEvent (VM452 easeljs.min.js:12)
    at a.b.dispatchEvent (VM452 easeljs.min.js:12)
    at Logo.runFromBlockNow (logo.js:1640)
    at logo.js:1474