This is the error value generally used and the calling function explicitly checks for -1, later causing the error to be missed and the transaction to continue.
pacman -S xterm warning: xterm-369-1 is up to date -- reinstalling resolving dependencies... looking for conflicting packages...
Package (1) Old Version New Version Net Change Download Size
extra/xterm 369-1 369-1 0.00 MiB 0.42 MiB
Total Download Size: 0.42 MiB Total Installed Size: 1.05 MiB Net Upgrade Size: 0.00 MiB
:: Proceed with installation? [Y/n] error: no servers configured for repository: extra (1/1) checking keys in keyring ------------------------------------------------------ 100% (1/1) checking package integrity ------------------------------------------------------ 100% error: failed to commit transaction (wrong or NULL argument passed) Errors occurred, no packages were upgraded.