Thanks for posting the log. Calamares was killed by the kernel OOM killer.
Dec 27 23:46:33 manjaro kernel: Out of memory: Killed process 2231 (calamares) total-vm:2589072kB, anon-rss:803852kB, file-rss:0kB, shmem-rss:5136kB, UID:0 pgtables:2360kB oom_score_adj:200
Dec 27 23:46:33 manjaro kernel: oom_reaper: reaped process 2231 (calamares), now anon-rss:0kB, file-rss:0kB, shmem-rss:4624kB
Dec 27 23:46:33 manjaro systemd[1]: user@1000.service: A process of this unit has been killed by the OOM killer.
Then we should probably increase the memory requirement to 4GB. Systems that shipped with 2GB RAM were never meant for 64-bit OSs to begin with.