Detect dependency plugins in candy-kingdom and kiwi themes

Fixes #5029
Fixes #5342

themes/candy-kingdom.zsh-theme

-# neuralsanwich.zsh-theme
-
-if [ "x$OH_MY_ZSH_HG" = "x" ]; then
-    OH_MY_ZSH_HG="hg"
-fi
-
-function hg_prompt_info {
-    $OH_MY_ZSH_HG prompt --angle-brackets "\
+if ! hg prompt 2>/dev/null; then
+    function hg_prompt_info { }
+else
+    function hg_prompt_info {
+        hg prompt --angle-brackets "\
 < on %{$fg[magenta]%}<branch>%{$reset_color%}>\
 < at %{$fg[yellow]%}<tags|%{$reset_color%}, %{$fg[yellow]%}>%{$reset_color%}>\
 %{$fg[green]%}<status|modified|unknown><update>%{$reset_color%}<
 patches: <patches|join( → )|pre_applied(%{$fg[yellow]%})|post_applied(%{$reset_color%})|pre_unapplied(%{$fg_bold[black]%})|post_unapplied(%{$reset_color%})>>" 2>/dev/null
-}
+    }
+fi
 
 function box_name {
     [ -f ~/.box-name ] && cat ~/.box-name || echo ${SHORT_HOST:-$HOST}
@@ -26,5 +24,9 @@ ZSH_THEME_GIT_PROMPT_UNTRACKED="%{$fg[red]%}?"
 ZSH_THEME_GIT_PROMPT_DIRTY="%{$fg[orange]%}!"
 ZSH_THEME_GIT_PROMPT_SUFFIX="%{$reset_color%})"
 
-local return_status="%{$fg[red]%}%(?..✘)%{$reset_color%}"
-RPROMPT='${return_status}$(battery_time_remaining) $(battery_pct_prompt)%{$reset_color%}'
+RPROMPT='%{$fg[red]%}%(?..✘)%{$reset_color%}'
+
+# Add battery status if the battery plugin is enabled
+if (( $+functions[battery_pct_prompt] )); then
+    RPROMPT+='$(battery_time_remaining) $(battery_pct_prompt)%{$reset_color%}'
+fi

themes/kiwi.zsh-theme

-# 
-# Kiwi ZSH Theme
-# 
+(( $+functions[battery_pct_prompt] )) || function battery_pct_prompt { }
 
 PROMPT='%{$fg_bold[green]%}┌[%{$fg_bold[cyan]%}kiwish-4.2%{$fg_bold[green]%}]-(%{$fg_bold[white]%}%2~%{$fg_bold[green]%})-$(git_prompt_info)$(svn_prompt_info)$(battery_pct_prompt)
 └> % %{$reset_color%}'