App crashes when using appdmg built with node 14

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MacOS High Sierra 10.13.6

NW.js 0.41.3 (node 12.12.0) works OK with appdmg installed with 12.18.0
NW.js 0.48.3 (node 14.11.0) FAILS with appdmg installed with 14.9.0

App crashes in the 'Making all the visuals' step. If the ds.write is skipped then appdmg will successfully create a DMG but with no visuals.

The code that is causing the issue is the ds.setBackgroundPath line - if this is commented out then again a good DMG will be created but with no background visuals.
The other bits of the visuals steps appear OK.

A console.log prior to this line shows the same format whether appdmg is using node 12 or 14 but only fails with 14 install.

appdmg.js L371 ds.setBackgroundPath(path.join(global.temporaryMountPath, global.bkgname))
gives eg: /Volumes/PepperFlash Install 18/.background/dmgback.tiff

Seems like appdmg installed with node 14 doesn't like tiff being written to the ds-store module.

The original image being used for the background was dmgback.png (82k) which obviously gets converted to a tiff.

appdmg.json -

{
"title": "PepperFlash Install",
"background": "Extras/dmg/dmgback.png",
"icon": "Extras/dmg/dmg.icns",
"contents": [
{
"x": 260,
"y": 350,
"type": "link",
"path": "/Applications"
},
{
"x": 90,
"y": 350,
"type": "file",
"path": "application.app"
},
{
"x": 490,
"y": 350,
"type": "file",
"path": "Extras/dmg/readme.txt"
},
{
"x": 512,
"y": 900,
"type": "position",
"path": ".VolumeIcon.icns"
}
]
}

Start at appdmg.js line 371, where ds.setBackgroundPath is called during the “Making all the visuals” step, and reproduce the failure with the supplied Node 14 and NW.js versions. Investigate the ds-store background-path handling; done means a DMG is created without crashing and retains its background visuals.

Written by the indexing model from the issue text.