Basically, the installer isn't building the game folder correctly (omits webview dll) which results in an error building the installer.exe.
Can resolve manually by copying the contents of the bin folder into the game folder and re-running the build script.
Error for completeness:
/*
File: "Kinfolk\WebView2Loader.dll" -> no files found.
Usage: File [/nonfatal] [/a] ([/r] [/x filespec [...]] filespec [...] |
/oname=outfile one_file_only)
!include: error in script: "install.nsh" on line 121
Error in script "C:\Users\folak\Desktop\The Town\byondexe\kinfolk.nsi" on line 10 -- aborting creation process
*/
Which isn't to say the byondexe tool is perfect by any stretch, because these kinds of situations come up way too much.