I've had another look at post #16223. The quoted code misses out the first line:
Code:
chmod +x /Users/aaron/Dev/Mojave/release-10.14/macOS\ Patcher.sh
I assume the file simply wouldn't run if it didn't have this permission but I've just downloaded a new copy of v2.3 of Julian Fairfax's patcher on an unsupported Mac (Mac mini 3,1) running High Sierra for testing. I've tried to create a new installer missing out the above line and the shell file runs to completion without error. At this point, I can only assume that there is something wrong with either your downloads or the disk that you are using. Given that the code shows that "Restoring Installer Disk Image" completed, I would assume that the Mojave file is ok and that you need to try a new drive.
*EDIT*
I've tried the above process with a drive that I know is too small for the installation files. This fails at the 'Patching graphics driver' section having successfully completed the following:
+Restored installer disk image.
+ Renamed installer volume.
+ Copied installer packages.
+ Copied installer disk images.
+ Unmounted installer disk images.
+ Replacing installer utilities menu.
+ Patched installer app.
+ Patched installer framework.
+ Patched system migration frameworks.
> Patching graphics driver.
The installer tells me that there isn't enough space to copy the files. So far, even having a drive that is correctly formatted but completely full doesn't introduce errors starting at 'Copying installer packages'. As I can't reproduce your error, I'm afraid I can't help you solve it. All I can deduce is that the patcher doesn't have write access to your installer drive, sorry.