diff --git a/lib/languages/lib/javascript.dart b/lib/languages/lib/javascript.dart
index 1692032..7d6e60b 100644
--- a/lib/languages/lib/javascript.dart
+++ b/lib/languages/lib/javascript.dart
@@ -1,20 +1,23 @@
 import 'package:re_highlight/re_highlight.dart';
 
-ModeCallback callbackOnBegin = (EnhancedMatch match, ModeCallbackResponse response) {
+ModeCallback callbackOnBegin =
+    (EnhancedMatch match, ModeCallbackResponse response) {
   final String? match0 = match[0];
   if (match0 == null) {
     return;
   }
   final int afterMatchIndex = match0.length + match.index;
-  final String nextChar = match.input.substring(afterMatchIndex, afterMatchIndex + 1);
+  final String? nextChar = afterMatchIndex < match.input.length
+      ? match.input[afterMatchIndex]
+      : null;
   if (
-    // HTML should not include another raw `<` inside a tag
-    // nested type?
-    // `<Array<Array<number>>`, etc.
-    nextChar == "<" ||
-    // the , gives away that this is not HTML
-    // `<T, A extends keyof T, V>`
-    nextChar == ",") {
+      // HTML should not include another raw `<` inside a tag
+      // nested type?
+      // `<Array<Array<number>>`, etc.
+      nextChar == "<" ||
+          // the , gives away that this is not HTML
+          // `<T, A extends keyof T, V>`
+          nextChar == ",") {
     response.ignoreMatch();
     return;
   }
@@ -57,4 +60,4 @@ bool _hasClosingTag(EnhancedMatch match, int after) {
   final String tag = "</${match[0]!.substring(1)}";
   final int pos = match.input.indexOf(tag, after);
   return pos != -1;
-}
\ No newline at end of file
+}
diff --git a/test/api/highlight_test.dart b/test/api/highlight_test.dart
index 70aa9b8..4a6f8db 100644
--- a/test/api/highlight_test.dart
+++ b/test/api/highlight_test.dart
@@ -10,43 +10,78 @@ void main() {
   group('.highlight()', () {
     test('should support ignoreIllegals', () {
       String code = "float # float";
-      HighlightResult result = highlight.highlight(code: code, language: 'java', ignoreIllegals: true);
-      expect(result.toHtml(), '<span class="hljs-type">float</span> # <span class="hljs-type">float</span>');
+      HighlightResult result = highlight.highlight(
+          code: code, language: 'java', ignoreIllegals: true);
+      expect(result.toHtml(),
+          '<span class="hljs-type">float</span> # <span class="hljs-type">float</span>');
 
       code = 'float # float';
-      result = highlight.highlight(code: code, language: 'java', ignoreIllegals: false);
+      result = highlight.highlight(
+          code: code, language: 'java', ignoreIllegals: false);
       expect(result.toHtml(), 'float # float');
       expect(result.illegal, true);
 
       // defaults to true
       code = 'float # float';
       result = highlight.highlight(code: code, language: 'java');
-      expect(result.toHtml(), '<span class="hljs-type">float</span> # <span class="hljs-type">float</span>');
+      expect(result.toHtml(),
+          '<span class="hljs-type">float</span> # <span class="hljs-type">float</span>');
       expect(result.illegal, false);
     });
+    test('should not crash on incomplete JSX-like tags at end of input', () {
+      const String code = 'const x = <Foo';
+      final Highlight safeHighlight = Highlight();
+      safeHighlight.registerLanguages(builtinAllLanguages);
+
+      HighlightResult result =
+          safeHighlight.highlight(code: code, language: 'javascript');
+      expect(result.errorRaised, isNull);
+      expect(() => result.toHtml(), returnsNormally);
+
+      result = safeHighlight.highlight(code: code, language: 'typescript');
+      expect(result.errorRaised, isNull);
+      expect(() => result.toHtml(), returnsNormally);
+
+      final Highlight debugHighlight = Highlight();
+      debugHighlight.debugMode();
+      debugHighlight.registerLanguages(builtinAllLanguages);
+
+      expect(
+          () => debugHighlight
+              .highlight(code: code, language: 'javascript')
+              .toHtml(),
+          returnsNormally);
+      expect(
+          () => debugHighlight
+              .highlight(code: code, language: 'typescript')
+              .toHtml(),
+          returnsNormally);
+    });
     test('should use new API with options', () {
       const String code = 'public void moveTo(int x, int y, int z);';
-      final HighlightResult result = highlight.highlight(code: code, language: 'java');
+      final HighlightResult result =
+          highlight.highlight(code: code, language: 'java');
 
-      expect(result.toHtml(),
-        '<span class="hljs-keyword">public</span> '
-        '<span class="hljs-keyword">void</span> <span class="hljs-title function_">moveTo</span>'
-        '<span class="hljs-params">(<span class="hljs-type">int</span> x, '
-        '<span class="hljs-type">int</span> y, '
-        '<span class="hljs-type">int</span> z)</span>;'
-      );
+      expect(
+          result.toHtml(),
+          '<span class="hljs-keyword">public</span> '
+          '<span class="hljs-keyword">void</span> <span class="hljs-title function_">moveTo</span>'
+          '<span class="hljs-params">(<span class="hljs-type">int</span> x, '
+          '<span class="hljs-type">int</span> y, '
+          '<span class="hljs-type">int</span> z)</span>;');
     });
     test('should works without continuation', () {
       const String code = "public void moveTo(int x, int y, int z);";
-      final HighlightResult result = highlight.highlight(code: code, language: 'java');
+      final HighlightResult result =
+          highlight.highlight(code: code, language: 'java');
 
-      expect(result.toHtml(),
-        '<span class="hljs-keyword">public</span> '
-        '<span class="hljs-keyword">void</span> <span class="hljs-title function_">moveTo</span>'
-        '<span class="hljs-params">(<span class="hljs-type">int</span> x, '
-        '<span class="hljs-type">int</span> y, '
-        '<span class="hljs-type">int</span> z)</span>;'
-      );
+      expect(
+          result.toHtml(),
+          '<span class="hljs-keyword">public</span> '
+          '<span class="hljs-keyword">void</span> <span class="hljs-title function_">moveTo</span>'
+          '<span class="hljs-params">(<span class="hljs-type">int</span> x, '
+          '<span class="hljs-type">int</span> y, '
+          '<span class="hljs-type">int</span> z)</span>;');
     });
   });
-}
\ No newline at end of file
+}