OC 0.5.9 - Mojave - Security Update 2020-005 won't install

hi all,

i built a new machine this summer, which runs mojave and at the time 0.5.9 was current.

i just got around to trying to install Security Update 2020-005, and it fails to install with the ultimate error:

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macOS Installer[592:34590] -[__NSCFString bytes]: unrecognized selector sent to instance 0x7ffc45f028b

there are a number of errors leading up to this point, but i don't know which are relevant.

some suspicious ones are:

IFJS: Package Authoring Error: error evaluating script active for choice SecUpd2020-005Mojave: TypeError: null is not an object (evaluating 'my.target.mountpoint') at x-distribution:///installer-gui-script%5B1%5D/choice%5B1%5D/pkg-ref%5B2%5D/@active ==> RecoveryHD7(my.target.mountpoint)

storagekitd: copyDiskForPath returned nil, error: -69808

unable to obtain configuration from file:///Library/Preferences/com.apple.ViewBridge.plist due to Error Domain=NSCocoaErrorDomain Code=260 "The file “com.apple.ViewBridge.plist” couldn’t be opened because there is no such file." UserInfo={NSFilePath=/Library/Preferences/com.apple.ViewBridge.plist, NSUnderlyingError=0x7ffc75c94dd0 {Error Domain=NSPOSIXErrorDomain Code=2 "No such file or directory"}}

one thing i can say is that this update has been pending for a long time, and i also have content caching turned on on this machine.

anyone seen this problem?

at the very least how do i get rid of the update from OCs boot picker/delete the installer image and make sure that OSX tries to download it and set it up from scratch again?