Nullish Coalescing Operator is more accurate for describing undefined comments length

Author: Janther

src/slang-printers/print-comments.ts

@@ -17,7 +17,7 @@ export function printComments(
   path: AstPath<PrintableNode>,
   options: ParserOptions<PrintableNode>
 ): Doc[] {
-  const lastPrintableIndex = (node.comments ?? []).findLastIndex(isPrintable);
+  const lastPrintableIndex = node.comments?.findLastIndex(isPrintable) ?? -1;
   if (lastPrintableIndex === -1) {
     return [];
   }

src/slang-printers/print-preserving-empty-lines.ts

@@ -44,7 +44,7 @@ export function printIndentedPreservingEmptyLines(
   print: PrintFunction,
   options: ParserOptions<PrintableNode>
 ): Doc {
-  return node.items.length > 0 || (node.comments?.length || 0) > 0
+  return node.items.length > 0 || (node.comments?.length ?? 0) > 0
     ? printSeparatedItem(
         printPreservingEmptyLines(node, path, print, options),
         { firstSeparator: hardline }