startupselfupdateinterval defaults to 0 on install

[dkav]

For both the standard and custom installs the startupselfupdateinterval defaults to 0 on installation despite the following statement provided during installation:

Julia will look for a new version of Juliaup itself every 1440 minutes when you start Julia.

▶ juliaup config startupselfupdateinterval             
   Configure Property 'startupselfupdateinterval' set to '0'

juliaupself.json is empty ({})

Installed on macOS 26.3 using:

curl -fsSL https://install.julialang.org | sh -s -- \
  --path "$XDG_DATA_HOME/juliaup"

Other update settings after install:

▶ juliaup config backgroundselfupdateinterval        
   Configure Property 'backgroundselfupdateinterval' set to '0'
▶ juliaup config versionsdbupdateinterval             
Property 'versionsdbupdateinterval' set to '1440'