..._invoke_original_widget: Return 0 when given no arguments

`_zsh_autosuggest_widget_accept()` (&al.) passes this function's return status
on, and ZLE rings the bell if it's >0. Not having an original widget isn't an
error condition, so always returning 0 here should be OK to avoid the bell

Fixes #228

src/bind.zsh

@@ -106,7 +106,7 @@ _zsh_autosuggest_bind_widgets() {
 # Given the name of an original widget and args, invoke it, if it exists
 _zsh_autosuggest_invoke_original_widget() {
 	# Do nothing unless called with at least one arg
-	(( $# )) || return
+	(( $# )) || return 0
 
 	local original_widget_name="$1"
 

zsh-autosuggestions.zsh

@@ -238,7 +238,7 @@ _zsh_autosuggest_bind_widgets() {
 # Given the name of an original widget and args, invoke it, if it exists
 _zsh_autosuggest_invoke_original_widget() {
 	# Do nothing unless called with at least one arg
-	(( $# )) || return
+	(( $# )) || return 0
 
 	local original_widget_name="$1"