Default empty first measure when fragmentizing

src/parsing/musicxml/measure.ts

@@ -134,6 +134,12 @@ export class Measure {
       fragments.push(Fragment.create(config, log, signature, buffer, partIds));
     }
 
+    // Ensure every measure has at least one fragment so the Part structure is preserved
+    // for empty measures (e.g. when <attributes> and notes are missing).
+    if (fragments.length === 0) {
+      fragments.push(Fragment.create(config, log, signature, [], partIds));
+    }
+
     return fragments;
   }
 

tests/__data__/vexml/empty_first_measure.musicxml

@@ -0,0 +1,25 @@
+<?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>

tests/integration/vexml.test.ts

@@ -42,6 +42,7 @@ describe('vexml', () => {
     { filename: 'tabs_vibrato.musicxml', width: 900 },
     { filename: 'tabs_bends.musicxml', width: 900 },
     { filename: 'chord_symbols.musicxml', width: 900 },
+    { filename: 'empty_first_measure.musicxml', width: 900 },
   ])(`$filename ($width px)`, async (t) => {
     const { document, vexmlDiv, screenshotElementSelector } = setup();