fix(repl): output error without hanging when input is invalid (#11426)

cli/tests/integration/repl_tests.rs

@@ -71,6 +71,23 @@ fn pty_bad_input() {
   });
 }
 
+#[cfg(unix)]
+#[test]
+fn pty_syntax_error_input() {
+  use std::io::{Read, Write};
+  run_pty_test(|master| {
+    master.write_all(b"('\\u')\n").unwrap();
+    master.write_all(b"('\n").unwrap();
+    master.write_all(b"close();\n").unwrap();
+
+    let mut output = String::new();
+    master.read_to_string(&mut output).unwrap();
+
+    assert!(output.contains("Unterminated string constant"));
+    assert!(output.contains("Unexpected eof"));
+  });
+}
+
 #[cfg(unix)]
 #[test]
 fn pty_complete_symbol() {

cli/tools/repl.rs

@@ -29,6 +29,7 @@ use std::borrow::Cow;
 use std::cell::RefCell;
 use std::path::PathBuf;
 use std::sync::Arc;
+use swc_ecmascript::parser::error::SyntaxError;
 use swc_ecmascript::parser::token::{Token, Word};
 use tokio::sync::mpsc::channel;
 use tokio::sync::mpsc::unbounded_channel;
@@ -257,6 +258,17 @@ impl Validator for EditorHelper {
               }
             }
           }
+          Token::Error(error) => {
+            match error.kind() {
+              // If there is unterminated template, it continues to read input.
+              SyntaxError::UnterminatedTpl => {}
+              _ => {
+                // If it failed parsing, it should be V8's task to output error instead.
+                // Thus marked as valid with no info.
+                return Ok(ValidationResult::Valid(None));
+              }
+            }
+          }
           _ => {}
         }
       }