Minimal MusicXML breaks when adding cursor

[jaredjj3]

Expected behavior
The following MusicXML document renders:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE score-partwise PUBLIC "-//Recordare//DTD MusicXML 1.0 Partwise//EN"
                                "http://www.musicxml.org/dtds/partwise.dtd">
<score-partwise>
  <movement-title>Pitches and accidentals</movement-title>
  <identification>
    <miscellaneous>
      <miscellaneous-field name="description">All pitches from G to c'''' in 
          ascending steps; First without accidentals, then with a sharp and then 
          with a flat accidental. Double alterations and cautionary accidentals 
          are tested at the end.</miscellaneous-field>
    </miscellaneous>
  </identification>
  <part-list>
    <score-part id="P1">
      <part-name>MusicXML Part</part-name>
    </score-part>
  </part-list>
  <!--=========================================================-->
  <part id="P1">
    <measure number="1">
    </measure>
  </part>
  <!--=========================================================-->
</score-partwise>

Actual behavior
Get the following error:

Error: partIndex out of bounds
    at _t (https://vexml.dev/assets/index-DKPwLc6p.js:49:47566)
    at Mv.addCursor (https://vexml.dev/assets/index-DKPwLc6p.js:49:1268768)
    at https://vexml.dev/assets/index-DKPwLc6p.js:69:12421
    at du (https://vexml.dev/assets/index-DKPwLc6p.js:48:82046)
    at Ex (https://vexml.dev/assets/index-DKPwLc6p.js:48:96806)
    at Qi (https://vexml.dev/assets/index-DKPwLc6p.js:48:96690)
    at Ex (https://vexml.dev/assets/index-DKPwLc6p.js:48:97487)
    at Qi (https://vexml.dev/assets/index-DKPwLc6p.js:48:96690)
    at Ex (https://vexml.dev/assets/index-DKPwLc6p.js:48:97487)
    at Qi (https://vexml.dev/assets/index-DKPwLc6p.js:48:96690)

Screenshot
N/A

Hints
It renders if the first measure specifies the following:

<attributes>
      <divisions>1</divisions>
      <clef>
        <sign>G</sign>
        <line>2</line>
      </clef>
    </attributes>