parse: refactored Beatmap impls

Cargo.toml

@@ -11,7 +11,7 @@ description = "osu! difficulty and pp calculation for all modes"
 keywords = ["osu", "pp", "stars", "async"]
 
 [features]
-default = ["osu", "taiko", "fruits", "mania", "no_leniency"]
+default = ["osu", "taiko", "fruits", "mania", "no_leniency", "async_tokio"]
 
 # game modes
 osu = []

src/lib.rs

@@ -473,6 +473,4 @@ compile_error!("Only one of the features `no_leniency`, `no_sliders_no_leniency`
 compile_error!("The features `no_leniency`, `no_sliders_no_leniency`, and `all_included` should only be enabled in combination with the `osu` feature");
 
 #[cfg(all(feature = "async_tokio", feature = "async_std"))]
-compile_error!(
+compile_error!("Only one of the async features `async_tokio` and `async_std` should be enabled");
-    "Only one of the two async features `async_tokio` and `async_std` should be enabled"
-);