Ok, my educated guess is that you installed the package from the official repositories, which is well known to have plenty of problems: Julia - ArchWiki. Evidence: the error message is pointing to
MbedTLS.jl/ssl.jl at 0c02e44ed96bf09ce3b9fb649db5914f629c2812 · JuliaLang/MbedTLS.jl · GitHub
and the variable MozillaCACerts_jll.cacert is apparently pointing to a non-existing file. You should direct your complaint to the maintainers of the Julia package in Arch Linux, who provide malfunctioning packages.
In the meantime I warmly recommend you to use the package aur:julia-bin which simply redistributes the official binaries.