show explicit error message when both crossterm and termion are not enabled

src/lib.rs

@@ -10,6 +10,14 @@
 ))]
 compile_error!("tui-rs support and ratatui support are exclussive. only one of them can be enabled at the same time. see https://github.com/rhysd/tui-textarea");
 
+#[cfg(not(any(
+    feature = "crossterm",
+    feature = "termion",
+    feature = "ratatui-crossterm",
+    feature = "ratatui-termion",
+)))]
+compile_error!("neither crossterm nor termion is enabled in features. see https://github.com/rhysd/tui-textarea");
+
 mod cursor;
 mod highlight;
 mod history;