julia> @edit 3+5
ERROR: could not find source file for function
Stacktrace:
[1] edit(::Nothing, ::Int32) at /build/julia/src/julia-1.5.3/usr/share/julia/stdlib/v1.5/InteractiveUtils/src/editless.jl:224
[2] edit(::Function, ::Any) at /build/julia/src/julia-1.5.3/usr/share/julia/stdlib/v1.5/InteractiveUtils/src/editless.jl:223
[3] top-level scope at REPL[167]:1
[4] run_repl(::REPL.AbstractREPL, ::Any) at /build/julia/src/julia-1.5.3/usr/share/julia/stdlib/v1.5/REPL/src/REPL.jl:288
Another user reports the problem as specific to the Manjaro package. i think it is usually better to use the official binaries. It is not rare to see problems in the packages shipped by the distributions themselves.