Designer will not fully open the ECMAScript editor for some ECMAScript objects.

When trying to open ECMAScript within Designer a new tab shows up for the script but the old view persists.

java.lang.Error: Unable to find a TraceInterface implementation

Designer's ECMAScript parser is failing to open the ECMAScript due to some of the content in the script, likely due to the use of a class for tracing.  Close the broken tab and instead right-click on the script object in Designer, go to 'Open With' and choose Text Editor.  The syntax highlighting and other IDE-like features will not work but editing the script is still allowed.