fix(updater): abort update if $ZSH is not a git repository

Fixes #12298

lib/cli.zsh

@@ -773,7 +773,17 @@ function _omz::theme::use {
 }
 
 function _omz::update {
-  local last_commit=$(builtin cd -q "$ZSH"; git rev-parse HEAD)
+  # Check if git command is available
+  (( $+commands[git] )) || {
+    _omz::log error "git is not installed. Aborting..."
+    return 1
+  }
+
+  local last_commit=$(builtin cd -q "$ZSH"; git rev-parse HEAD 2>/dev/null)
+  [[ $? -eq 0 ]] || {
+    _omz::log error "\`$ZSH\` is not a git directory. Aborting..."
+    return 1
+  }
 
   # Run update script
   zstyle -s ':omz:update' verbose verbose_mode || verbose_mode=default

tools/check_for_upgrade.sh

@@ -20,14 +20,16 @@ zstyle -s ':omz:update' mode update_mode || {
 }
 
 # Cancel update if:
-# - the automatic update is disabled.
-# - the current user doesn't have write permissions nor owns the $ZSH directory.
+# - the automatic update is disabled
+# - the current user doesn't have write permissions nor owns the $ZSH directory
 # - is not run from a tty
-# - git is unavailable on the system.
+# - git is unavailable on the system
+# - $ZSH is not a git repository
 if [[ "$update_mode" = disabled ]] \
    || [[ ! -w "$ZSH" || ! -O "$ZSH" ]] \
    || [[ ! -t 1 ]] \
-   || ! command git --version 2>&1 >/dev/null; then
+   || ! command git --version 2>&1 >/dev/null
+   || (builtin cd -q "$ZSH"; ! command git rev-parse --is-inside-work-tree &>/dev/null); then
   unset update_mode
   return
 fi