Assume latest if no ol.VERSION

src/ol/assertionerror.js

@@ -13,11 +13,12 @@ goog.require('ol');
  */
 ol.AssertionError = function(code) {
 
+  var path = ol.VERSION ? ol.VERSION.split('-')[0] : 'latest';
+
   /**
    * @type {string}
    */
-  this.message = 'Assertion failed. See ' +
+  this.message = 'Assertion failed. See https://openlayers.org/en/' + path +
-      (ol.VERSION ? 'https://openlayers.org/en/' + ol.VERSION.split('-')[0] : '') +
       '/doc/errors/#' + code + ' for details.';
 
   /**

test/spec/ol/assertionerror.test.js

@@ -6,8 +6,9 @@ goog.require('ol.AssertionError');
 describe('ol.AssertionError', function() {
   it('generates a message', function() {
     var error = new ol.AssertionError(42);
-    expect(error.message).to.be('Assertion failed. See /doc/errors/#42 for details.');
+    expect(error.message).to.be('Assertion failed. See https://openlayers.org/en/latest/doc/errors/#42 for details.');
   });
+
   it('generates a message with a versioned url', function() {
     var origVersion = ol.VERSION;
     ol.VERSION = 'foo';
@@ -15,10 +16,12 @@ describe('ol.AssertionError', function() {
     expect(error.message).to.be('Assertion failed. See https://openlayers.org/en/foo/doc/errors/#42 for details.');
     ol.VERSION = origVersion;
   });
+
   it('has an error code', function() {
     var error = new ol.AssertionError(42);
     expect(error.code).to.be(42);
   });
+
   it('has a name', function() {
     var error = new ol.AssertionError(42);
     expect(error.name).to.be('AssertionError');