fix(cli): allow `omz` commands to be used in a script (#10645)

The commands `omz plugin {enable,disable}` and `omz theme set`
automatically reload the zsh session on success. With this
change, the CLI checks whether the commands are run in an
interactive session before reloading the zsh session.

This change also conditionally sets the completion function
for `omz` so that it's not done in a non-interactive session.

lib/cli.zsh

@@ -105,7 +105,10 @@ function _omz {
   return 0
 }
 
-compdef _omz omz
+# If run from a script, do not set the completion function
+if (( ${+functions[compdef]} )); then
+  compdef _omz omz
+fi
 
 ## Utility functions
 
@@ -299,10 +302,8 @@ multi == 1 && length(\$0) > 0 {
   # Restart the zsh session if there were no errors
   _omz::log info "plugins disabled: ${(j:, :)dis_plugins}."
 
-  # Old zsh versions don't have ZSH_ARGZERO
-  local zsh="${ZSH_ARGZERO:-${functrace[-1]%:*}}"
-  # Check whether to run a login shell
-  [[ "$zsh" = -* || -o login ]] && exec -l "${zsh#-}" || exec "$zsh"
+  # Only reload zsh if run in an interactive session
+  [[ ! -o interactive ]] || _omz::reload
 }
 
 function _omz::plugin::enable {
@@ -375,10 +376,8 @@ multi == 1 && /^[^#]*\)/ {
   # Restart the zsh session if there were no errors
   _omz::log info "plugins enabled: ${(j:, :)add_plugins}."
 
-  # Old zsh versions don't have ZSH_ARGZERO
-  local zsh="${ZSH_ARGZERO:-${functrace[-1]%:*}}"
-  # Check whether to run a login shell
-  [[ "$zsh" = -* || -o login ]] && exec -l "${zsh#-}" || exec "$zsh"
+  # Only reload zsh if run in an interactive session
+  [[ ! -o interactive ]] || _omz::reload
 }
 
 function _omz::plugin::info {
@@ -731,10 +730,8 @@ EOF
   # Restart the zsh session if there were no errors
   _omz::log info "'$1' theme set correctly."
 
-  # Old zsh versions don't have ZSH_ARGZERO
-  local zsh="${ZSH_ARGZERO:-${functrace[-1]%:*}}"
-  # Check whether to run a login shell
-  [[ "$zsh" = -* || -o login ]] && exec -l "${zsh#-}" || exec "$zsh"
+  # Only reload zsh if run in an interactive session
+  [[ ! -o interactive ]] || _omz::reload
 }
 
 function _omz::theme::use {