From 9a039b907d88f92ff38ba842cd5c4c905273d1a0 Mon Sep 17 00:00:00 2001
From: Iban Eguia Moraza <razican@protonmail.ch>
Date: Sun, 27 Feb 2022 17:57:17 +0100
Subject: [PATCH 1/3] Removing the panic in favour of an error result

---
 boa_engine/src/bytecompiler.rs | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/boa_engine/src/bytecompiler.rs b/boa_engine/src/bytecompiler.rs
index 1f4550a98da..ad2590baa6b 100644
--- a/boa_engine/src/bytecompiler.rs
+++ b/boa_engine/src/bytecompiler.rs
@@ -1510,11 +1510,12 @@ impl<'b> ByteCompiler<'b> {
                             break;
                         }
                     }
-                    assert!(
-                        found,
-                        "Undefined label '{}'",
-                        self.interner().resolve_expect(label_name)
-                    );
+                    if !found {
+                        return self.context.throw_syntax_error(format!(
+                            "Cannot use the undeclared label '{}",
+                            self.interner().resolve_expect(label_name)
+                        ));
+                    }
                 } else {
                     self.jump_info
                         .last_mut()

From f1b2c6a8638c298e0194f1763e6a9519789f7ed2 Mon Sep 17 00:00:00 2001
From: Iban Eguia Moraza <razican@protonmail.ch>
Date: Sun, 27 Feb 2022 17:59:53 +0100
Subject: [PATCH 2/3] Fixed the single quote in error message

---
 boa_engine/src/bytecompiler.rs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/boa_engine/src/bytecompiler.rs b/boa_engine/src/bytecompiler.rs
index ad2590baa6b..cfb05d3381d 100644
--- a/boa_engine/src/bytecompiler.rs
+++ b/boa_engine/src/bytecompiler.rs
@@ -1512,7 +1512,7 @@ impl<'b> ByteCompiler<'b> {
                     }
                     if !found {
                         return self.context.throw_syntax_error(format!(
-                            "Cannot use the undeclared label '{}",
+                            "Cannot use the undeclared label '{}'",
                             self.interner().resolve_expect(label_name)
                         ));
                     }

From d8cd599538d199855277ae825c718432dcf7cda1 Mon Sep 17 00:00:00 2001
From: Iban Eguia Moraza <razican@protonmail.ch>
Date: Sun, 27 Feb 2022 18:31:02 +0100
Subject: [PATCH 3/3] Fixed test

---
 boa_engine/src/tests.rs | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/boa_engine/src/tests.rs b/boa_engine/src/tests.rs
index 1d8176012a0..b93da4cc1c5 100644
--- a/boa_engine/src/tests.rs
+++ b/boa_engine/src/tests.rs
@@ -431,7 +431,6 @@ fn for_loop_iteration_variable_does_not_leak() {
 }
 
 #[test]
-#[should_panic]
 fn test_invalid_break_target() {
     let src = r#"
         while (false) {
@@ -439,7 +438,7 @@ fn test_invalid_break_target() {
         }
         "#;
 
-    let _ = &exec(src);
+    assert!(Context::default().eval(src).is_err());
 }
 
 #[test]