Send errors to stderr (#3336)

* fix: send errors to stderr by default (#2561)

Closes #2561

* chore: add changelog entry

* chore: change PR id

* chore: add github username

* chore: cargo fmt...

* chore: move changelog line to bugfixes

tests/integration_tests.rs

@@ -450,6 +450,16 @@ fn stdin_to_stdout_cycle() -> io::Result<()> {
     Ok(())
 }
 
+#[cfg(unix)]
+#[test]
+fn bat_error_to_stderr() {
+    bat()
+        .arg("/tmp")
+        .assert()
+        .failure()
+        .stderr(predicate::str::contains("[bat error]"));
+}
+
 #[cfg(unix)]
 #[test]
 fn no_args_doesnt_break() {