I just saw something very similar when trying to export a PNG on OSX. I think in this case it was because the export window defaulted to the root of my HDD and my user doesn't have write permissions there. Picking a folder in my userspace fixed it but a more user-friendly error message would be good here.
Uncaught Exception:
Error: EACCES: permission denied, open '/awesome.png.__new__'
at Error (native)
at Object.fs.openSync (fs.js:640:18)
at Object.module.(anonymous function) [as openSync] (ELECTRON_ASAR.js:178:20)
at Object.fs.writeFileSync (fs.js:1343:33)
at writeFileSync (/Users/eliot/Applications/Subform.app/Contents/Resources/app.asar/node_modules/fs-jetpack/lib/write.js:32:8)
at writeAtomicSync (/Users/eliot/Applications/Subform.app/Contents/Resources/app.asar/node_modules/fs-jetpack/lib/write.js:48:3)
at Object.writeSync [as sync] (/Users/eliot/Applications/Subform.app/Contents/Resources/app.asar/node_modules/fs-jetpack/lib/write.js:61:3)
at Object.write (/Users/eliot/Applications/Subform.app/Contents/Resources/app.asar/node_modules/fs-jetpack/lib/jetpack.js:211:13)
at /Users/eliot/Applications/Subform.app/Contents/Resources/app.asar/main.js:97:10
at Function.<anonymous> (/Users/eliot/Applications/Subform.app/Contents/Resources/app.asar/render_html.js:52:13)