exporting assets will crash generator

I found that when export image in photoshop, like using code

app.activeDocument.exportDocument(file, ExportType.SAVEFORWEB, options);

or manully use the ps Export -> Save for web...

this will make an exception to generator process and stop it

Ps then shows an error dialog

generator exception log, just show "Unknown Javascript Error"

this is the code which output the error and stop the process

as I have a Geneartor plugin running background, when user export assets (or using some exporting panels), the generator process get stoped,  and my plugin get down too...

is this a bug of the "exporting progress" or something? 

and can it be fixed?

thanks.