And here is what the log says:
12:12:10.519865 +0100 system_installd PKG: pre-install scripts for "com.apple.pkg.Safari13.0.4HighSierraAuto"
com.apple.message.uuid: B7EEFC7A-84E1-44D7-B946-A201E2248C7A
com.apple.message.result: success
com.apple.message.value: 0.15447
com.apple.message.domain: com.apple.PackageKit.install.package.preinstall
com.apple.message.signature: SUCCESS: com.apple.pkg.Safari13.0.4HighSierraAuto
com.apple.message.signature2: 1.0.0.0.1.1574379006
SenderMachUUID: DDCD65D9-8F01-3B46-A2A8-A6D2FFAB02F0
12:12:10.521115 +0100 system_installd PKG: applying system content rules for "com.apple.pkg.macOSBrain, com.apple.pkg.Safari13.0.4HighSierraAuto"
Error Domain=PKInstallErrorDomain Code=119 "An error occurred while setting file attributes." UserInfo={NSURL=file:///Library/Updates/061-45391/macOSBrain.pkg, PKInstallPackageIdentifier=com.apple.pkg.macOSBrain, NSLocalizedDescription=An error occurred while setting file attributes.} {
NSLocalizedDescription = "An error occurred while setting file attributes.";
NSURL = "file:///Library/Updates/061-45391/macOSBrain.pkg";
PKInstallPackageIdentifier = "com.apple.pkg.macOSBrain";
}
com.apple.message.uuid: B7EEFC7A-84E1-44D7-B946-A201E2248C7A
com.apple.message.domain: com.apple.PackageKit.install.package.applySystemContentRules
com.apple.message.signature: FAILURE: softwareupdated
com.apple.message.result: failure
com.apple.message.value: 0.00106
SenderMachUUID: DDCD65D9-8F01-3B46-A2A8-A6D2FFAB02F0
12:12:11.027011 +0100 system_installd REQ: install failed
com.apple.message.uuid: B7EEFC7A-84E1-44D7-B946-A201E2248C7A
com.apple.message.domain: com.apple.PackageKit.install
com.apple.message.signature: FAILURE: softwareupdated
com.apple.message.result: failure
com.apple.message.value: 6.76665
SenderMachUUID: DDCD65D9-8F01-3B46-A2A8-A6D2FFAB02F0
12:12:11.304527 +0100 softwareupdated SWU: installing "Security Update 2019-007, 10.13.6"
com.apple.message.uuid: B7EEFC7A-84E1-44D7-B946-A201E2248C7A
com.apple.message.domain: com.apple.SoftwareUpdate.install
com.apple.message.result: failure
com.apple.message.signature: FAILURE: 061-45391
com.apple.message.signature2: softwareupdated
com.apple.message.signature3: PKInstallErrorDomain, 119
SenderMachUUID: F415F492-1420-3CAA-877F-6463517F3ADB
12:12:11.304630 +0100 softwareupdated SWU: installing "Safari, 13.0.4"
com.apple.message.uuid: B7EEFC7A-84E1-44D7-B946-A201E2248C7A
com.apple.message.domain: com.apple.SoftwareUpdate.install
com.apple.message.signature: FAILURE: 061-49180
com.apple.message.result: failure
com.apple.message.signature2: softwareupdated
com.apple.message.signature3: PKInstallErrorDomain, 119
SenderMachUUID: F415F492-1420-3CAA-877F-6463517F3ADB