Fix: undefined canvas (var was in wrong scope)

dmnverifierfrontend/src/main/resources/META-INF/resources/js/dmnViewer.js

@@ -16,14 +16,14 @@ $(document).ready(function () {
     // calc height
     if ($(".dmn-js-parent").hasClass('fullscreen')) {
       $(".dmn-js-parent").css('height', '');
-      var activeEditor = dmnModeler.getActiveViewer();
-      // access active editor components
-      var canvas = activeEditor.get('canvas');
     } else {
       let dmnModelerHeight = $(window).height() / 2.5;
       $(".dmn-js-parent").css('height', dmnModelerHeight + 'px');
     }
     // zoom to fit full viewport
+    var activeEditor = dmnModeler.getActiveViewer();
+    // access active editor components
+    var canvas = activeEditor.get('canvas');
     canvas.zoom('fit-viewport');
   });
 });