Ensure $key_info is populated before use

modules/history-substring-search/init.zsh

@@ -28,6 +28,7 @@ fi
 # Key Bindings
 #
 
+if [[ -n $key_info ]]; then
   # Emacs
   bindkey -M emacs "$key_info[Control]P" history-substring-search-up
   bindkey -M emacs "$key_info[Control]N" history-substring-search-down
@@ -41,4 +42,5 @@ for keymap in 'emacs' 'viins'; do
     bindkey -M "$keymap" "$key_info[Up]" history-substring-search-up
     bindkey -M "$keymap" "$key_info[Down]" history-substring-search-down
   done
+fi