Allow zero as first level start number

Giuseppe Criscione · Giuseppe Criscione · commit 0987fe72009f · 2025-10-01T12:44:51.000+02:00
diff --git a/src/file/numbering/numbering.ts b/src/file/numbering/numbering.ts
@@ -202,7 +202,7 @@ export class Numbering extends XmlComponent {
             reference,
             instance,
             overrideLevels: [
-                firstLevelStartNumber && Number.isInteger(firstLevelStartNumber)
+                firstLevelStartNumber !== undefined && Number.isInteger(firstLevelStartNumber)
                     ? {
                           num: 0,
                           start: firstLevelStartNumber,
