Fix missing chars with pdfjs

 # Changelog
 
+## 3.7.1
+
+- Fix missing chars with pdfjs
+
 ## 3.7.0
 
 - Fix imports for Dart 2.15

@@ -76,8 +76,12 @@ class TtfWriter {
         continue;
       }
 
-      final glyph =
-          ttf.readGlyph(ttf.charToGlyphIndexMap[chars[index]] ?? 0).copy();
+      final glyphIndex = ttf.charToGlyphIndexMap[chars[index]] ?? 0;
+      if (glyphIndex >= ttf.glyphOffsets.length) {
+        continue;
+      }
+
+      final glyph = ttf.readGlyph(glyphIndex).copy();
       for (final g in glyph.compounds) {
         compounds[g] = -1;
       }

@@ -23,7 +23,7 @@ class PdfUnicodeCmap extends PdfObjectStream {
   PdfUnicodeCmap(PdfDocument pdfDocument, this.protect) : super(pdfDocument);
 
   /// List of characters
-  final cmap = <int>[];
+  final cmap = <int>[0];
 
   /// Protects the text from being "seen" by the PDF reader.
   final bool protect;

@@ -3,7 +3,7 @@ description: A pdf producer for Dart. It can create pdf files for both web or fl
 homepage: https://github.com/DavBfr/dart_pdf/tree/master/pdf
 repository: https://github.com/DavBfr/dart_pdf
 issue_tracker: https://github.com/DavBfr/dart_pdf/issues
-version: 3.7.0
+version: 3.7.1
 
 environment:
   sdk: ">=2.12.0 <3.0.0"

@@ -22,7 +22,7 @@ dependencies:
   image: ">=3.0.1 <4.0.0"
   js: ^0.6.3
   meta: ">=1.3.0 <2.0.0"
-  pdf: ^3.7.0
+  pdf: ^3.7.1
   plugin_platform_interface: ^2.0.0
 
 dev_dependencies: