lang: Fix `len_from_type` typo in `Option` type error msg (#3526)

lang/derive/space/src/lib.rs

@@ -132,7 +132,7 @@ fn len_from_type(ty: Type, attrs: &mut Option<VecDeque<TokenStream2>>) -> TokenS
 
                         quote!((1 + #type_len))
                     } else {
-                        quote_spanned!(ident.span() => compile_error!("Invalid argument in Vec"))
+                        quote_spanned!(ident.span() => compile_error!("Invalid argument in Option"))
                     }
                 }
                 "Vec" => {