Update fish files to return instead of exit for consistency

hooks/base16-fzf.fish

@@ -18,7 +18,7 @@ end
 
 # If BASE16_FZF_PATH doesn't exist, stop hook
 if not test -d "$BASE16_FZF_PATH"
-  exit 2
+  return 2
 end
 
 # ----------------------------------------------------------------------

hooks/base16-hexchat.fish

@@ -18,20 +18,20 @@ end
 
 # If BASE16_HEXCHAT_PATH doesn't exist, stop hook
 if not test -d "$BASE16_HEXCHAT_PATH"
-  exit 2
+  return 2
 end
 
 # If HEXCHAT_COLORS_CONF_PATH hasn't been configured, stop hook
 if test -z "$HEXCHAT_COLORS_CONF_PATH"
-  exit 1
+  return 1
 end
 
 # If HEXCHAT_COLORS_CONF_PATH has been configured, but the file doesn't
 # exist
 if test -n "$HEXCHAT_COLORS_CONF_PATH"; \
   and not test -f "$HEXCHAT_COLORS_CONF_PATH"
   echo "\$HEXCHAT_COLORS_CONF_PATH is not a file."
-  exit 2
+  return 2
 end
 
 # Set current theme name
@@ -47,7 +47,7 @@ if not test -f "$hexchat_theme_path"
 
   echo $output
 
-  exit 2
+  return 2
 end
 
 # ----------------------------------------------------------------------

hooks/base16-tmux.fish

@@ -22,7 +22,7 @@ end
 
 # If base16-tmux path directory doesn't exist, stop hook
 if not test -d $BASE16_TMUX_PLUGIN_PATH
-  exit 2
+  return 2
 end
 
 # ----------------------------------------------------------------------