Uncaught TypeError: savePath.lastIndexOf is not a function

[Light-beariing]

When I preview the UML and save it as a photo, the error appears.
The error stack trace is here:

E:\Users\XXX\.atom\packages\plantuml-viewer\lib\plantuml-viewer-view.js:189
[Hide Stack Trace](https://github.com/markushedvall/plantuml-viewer/issues/new#)
TypeError: savePath.lastIndexOf is not a function
    at saveAs (E:\Users\XXX\.atom\packages\plantuml-viewer\lib\plantuml-viewer-view.js:189:48)
    at HTMLDivElement.<anonymous> (E:\Users\XXX\.atom\packages\plantuml-viewer\lib\plantuml-viewer-view.js:99:7)
    at CommandRegistry.handleCommandEvent (E:\Users\XXX\AppData\Local\atom\app-1.60.0\resources\app\static\<embedded>:11:352694)
    at CommandRegistry.dispatch (E:\Users\XXX\AppData\Local\atom\app-1.60.0\resources\app\static\<embedded>:11:351169)
    at AtomEnvironment.dispatchContextMenuCommand (E:\Users\JhnAmeTing\AppData\Local\atom\app-1.60.0\resources\app\static\<embedded>:1:833477)
    at EventEmitter.t (E:\Users\XXX\AppData\Local\atom\app-1.60.0\resources\app\static\<embedded>:1:841531)
    at EventEmitter.emit (events.js:223:5)
    at Object.onMessage (electron/js2c/renderer_init.js:115:818)