The next question (for background see Interpolate into an AppleScript called through Cmd).
When calling AppleScript from the shell, the redirection works as expected:
eben60@Macmini ~ % osascript -e 'POSIX path of (choose folder with prompt "Pick a folder:")'
2024-12-13 22:29:28.938 osascript[92280:10059569] +[IMKClient subclass]: chose IMKClient_Modern
/Users/eben60/Downloads/2023/
Without redirection: the line starting with 2024-12-13 is “log noise”, the third line is the directory selected.
eben60@Macmini ~ % osascript -e 'POSIX path of (choose folder with prompt "Pick a folder:")' 2> /dev/null
/Users/eben60/Downloads/2023/
With redirection: the error/warning/log message disappears in /dev/null as expected.
Now the same from Julia shell:
julia> script12 = """POSIX path of (choose folder with prompt "Pick a folder:")""";
julia> r12 = readchomp(`osascript -e $script12 2\> /dev/null`); # dialog opens
2024-12-13 22:39:12.192 osascript[92481:10066803] +[IMKClient subclass]: chose IMKClient_Modern
julia> r12
"/Users/eben60/Downloads/2023/"
Redirection ignored