old_contents: var tape = require('tape');
  var mjAPI = require("../lib/main.js");
  mjAPI.config({undefinedCharError: true});
  
  tape('basic test: check warnings', function (t) {
      t.plan(2);
      mjAPI.typeset({math:'呵', html:true})
          .catch(errors => t.ok(errors, 'CommonHTML output reports error'));
      mjAPI.typeset({math:'呵', svg:true})
          .catch(errors => t.ok(errors, 'SVG output reports error'));
  });
  
new_contents: var tape = require('tape');
  var mjAPI = require("../lib/main.js");
  mjAPI.config({undefinedCharError: true});
  
  tape('basic test: check warnings', function (t) {
      t.plan(2);
      mjAPI.typeset({math:'\u5475', html:true})
          .catch(errors => t.ok(errors, 'CommonHTML output reports error'));
      mjAPI.typeset({math:'\u5475', svg:true})
          .catch(errors => t.ok(errors, 'SVG output reports error'));
  });
  
subject: change unicode reference