fix(typescript): don't crash on statementless loop label in declare namespace

Parser::parse_and_visit_statement returns false for a statementless
loop label, leading to an assertion failure. Remove the incorrect
assertion.

Author: strager

src/quick-lint-js/fe/parse-statement.cpp

@@ -3399,13 +3399,14 @@ void Parser::parse_and_visit_typescript_declare_block(
       } else {
         // require_declaration will cause parse_and_visit_statement to report
         // Diag_Declare_Namespace_Cannot_Contain_Statement.
-        bool parsed_statement = this->parse_and_visit_statement(
-            v, Parse_Statement_Options{
-                   .possibly_followed_by_another_statement = true,
-                   .require_declaration = true,
-                   .declare_keyword = declare_context.declare_keyword_span(),
-               });
-        QLJS_ASSERT(parsed_statement);
+        [[maybe_unused]] bool parsed_statement =
+            this->parse_and_visit_statement(
+                v,
+                Parse_Statement_Options{
+                    .possibly_followed_by_another_statement = true,
+                    .require_declaration = true,
+                    .declare_keyword = declare_context.declare_keyword_span(),
+                });
       }
       break;
 

test/test-parse-typescript-declare-namespace.cpp

@@ -1067,6 +1067,18 @@ TEST_F(Test_Parse_TypeScript_Declare_Namespace,
                             non_empty_namespace_decl(u8"ns"_sv)));
   }
 }
+
+TEST_F(Test_Parse_TypeScript_Declare_Namespace,
+       declare_namespace_cannot_contain_loop_label) {
+  test_parse_and_visit_module(
+      u8"declare namespace ns { label: export class C {} }"_sv,
+      u8"                       ^^^^^ Diag_Declare_Namespace_Cannot_Contain_Statement.first_statement_token"_diag,
+      typescript_options);
+  test_parse_and_visit_module(
+      u8"declare namespace ns { label: }"_sv,
+      u8"                       ^^^^^ Diag_Declare_Namespace_Cannot_Contain_Statement.first_statement_token"_diag,
+      typescript_options);
+}
 }
 }