diff --git a/sway-core/src/semantic_analysis/ast_node/declaration/impl_trait.rs b/sway-core/src/semantic_analysis/ast_node/declaration/impl_trait.rs
index 5eca8e967d3..109bd8669d9 100644
--- a/sway-core/src/semantic_analysis/ast_node/declaration/impl_trait.rs
+++ b/sway-core/src/semantic_analysis/ast_node/declaration/impl_trait.rs
@@ -489,7 +489,12 @@ impl TyImplSelfOrTrait {
                             (ImplItem::Type(_type_decl), TyTraitItem::Type(_decl_ref)) => {
                                 // Already processed.
                             }
-                            _ => unreachable!(),
+                            _ => {
+                                handler.emit_err(CompileError::Internal(
+                                    "Unexpected ImplItem tuple.",
+                                    Span::dummy(),
+                                ));
+                            }
                         }
                     }
 
@@ -542,7 +547,12 @@ impl TyImplSelfOrTrait {
                             (ImplItem::Type(_type_decl), TyTraitItem::Type(_decl_ref)) => {
                                 // Already processed.
                             }
-                            _ => unreachable!(),
+                            _ => {
+                                handler.emit_err(CompileError::Internal(
+                                    "Unexpected ImplItem tuple.",
+                                    Span::dummy(),
+                                ));
+                            }
                         }
                     }
 
diff --git a/test/src/e2e_vm_tests/test_programs/should_fail/lexer_errors/.gitignore b/test/src/e2e_vm_tests/test_programs/should_fail/lexer_errors/.gitignore
new file mode 100644
index 00000000000..77d3844f58c
--- /dev/null
+++ b/test/src/e2e_vm_tests/test_programs/should_fail/lexer_errors/.gitignore
@@ -0,0 +1,2 @@
+out
+target
diff --git a/test/src/e2e_vm_tests/test_programs/should_fail/lexer_errors/Forc.lock b/test/src/e2e_vm_tests/test_programs/should_fail/lexer_errors/Forc.lock
new file mode 100644
index 00000000000..d8670265e2e
--- /dev/null
+++ b/test/src/e2e_vm_tests/test_programs/should_fail/lexer_errors/Forc.lock
@@ -0,0 +1,8 @@
+[[package]]
+name = "core"
+source = "path+from-root-082ED3C1A64D1BB4"
+
+[[package]]
+name = "lexer_errors"
+source = "member"
+dependencies = ["core"]
diff --git a/test/src/e2e_vm_tests/test_programs/should_fail/lexer_errors/Forc.toml b/test/src/e2e_vm_tests/test_programs/should_fail/lexer_errors/Forc.toml
new file mode 100644
index 00000000000..1b354765afa
--- /dev/null
+++ b/test/src/e2e_vm_tests/test_programs/should_fail/lexer_errors/Forc.toml
@@ -0,0 +1,9 @@
+[project]
+authors = ["Fuel Labs <contact@fuel.sh>"]
+entry = "main.sw"
+license = "Apache-2.0"
+name = "lexer_errors"
+implicit-std = false
+
+[dependencies]
+core = { path = "../../../../../../sway-lib-core" }
diff --git a/test/src/e2e_vm_tests/test_programs/should_fail/lexer_errors/src/main.sw b/test/src/e2e_vm_tests/test_programs/should_fail/lexer_errors/src/main.sw
new file mode 100644
index 00000000000..2afd00663ab
--- /dev/null
+++ b/test/src/e2e_vm_tests/test_programs/should_fail/lexer_errors/src/main.sw
@@ -0,0 +1,15 @@
+library;
+
+pub struct R {
+    a: u32,
+}
+
+impl R {
+    pub fn from_str(new: i32) {
+p() {
+  :Script => {
+   c = ZERO_B256;
+    ), }
+}
+
+const OFFSET = 0;
\ No newline at end of file
diff --git a/test/src/e2e_vm_tests/test_programs/should_fail/lexer_errors/test.toml b/test/src/e2e_vm_tests/test_programs/should_fail/lexer_errors/test.toml
new file mode 100644
index 00000000000..1564ded8e80
--- /dev/null
+++ b/test/src/e2e_vm_tests/test_programs/should_fail/lexer_errors/test.toml
@@ -0,0 +1,8 @@
+category = "fail"
+
+# check: $()error
+# check: $()mismatched delimiters
+
+# check: $()error
+# check: $()impl R {
+# nextln: $()unclosed delimiter
\ No newline at end of file