In the release notes for SetupBuilder 2018 Version 10 Build 6074, the following is listed:

CHANGE: Installer: When SetupBuilder failed to extract its temporary system files to the temp directory (either because of an anti-virus or permissions issues), it reported the error with a popup, but did not have a return code of non-zero to indicate an error. For automated installations there were no way to know that it encountered an error. It returns a non-zero exit code in this case now.

However, this does not appear to be the behavior. If the temp directory is not accessible, the following dialog appears, and the return code from the installer is zero.

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