fix(rkj-repos): check if `~/.hgrc` exists (#12148)

themes/rkj-repos.zsh-theme

@@ -1,7 +1,7 @@
 # user, host, full path, and time/date on two lines for easier vgrepping
 
 function hg_prompt_info {
-  if (( $+commands[hg] )) && grep -q "prompt" ~/.hgrc; then
+  if (( $+commands[hg] )) && [[ -e ~/.hgrc ]] && grep -q "prompt" ~/.hgrc; then
     hg prompt --angle-brackets "\
 <hg:%{$fg[magenta]%}<branch>%{$reset_color%}><:%{$fg[magenta]%}<bookmark>%{$reset_color%}>\
 </%{$fg[yellow]%}<tags|%{$reset_color%}, %{$fg[yellow]%}>%{$reset_color%}>\