diff -r 19b4ddc302a6 -r d1e482f73507 javaquery/api/src/main/java/org/apidesign/bck2brwsr/htmlpage/ConvertTypes.java
--- a/javaquery/api/src/main/java/org/apidesign/bck2brwsr/htmlpage/ConvertTypes.java	Fri Apr 05 12:43:17 2013 +0200
+++ b/javaquery/api/src/main/java/org/apidesign/bck2brwsr/htmlpage/ConvertTypes.java	Sun Apr 07 17:42:50 2013 +0200
@@ -80,7 +80,11 @@
         + "request.setRequestHeader('Content-Type', 'application/json; charset=utf-8');\n"
         + "request.onreadystatechange = function() {\n"
         + "  if (this.readyState!==4) return;\n"
-        + "  arr[0] = eval('(' + this.response + ')');\n"
+        + "  try {\n"
+        + "    arr[0] = eval('(' + this.response + ')');\n"
+        + "  } catch (error) {;\n"
+        + "    throw 'Cannot parse' + error + ':' + this.response;\n"
+        + "  };\n"
         + "  callback.run__V();\n"
         + "};"
         + "request.send();"