add empty address test

compiler/tests/address/empty.leo

@@ -0,0 +1,3 @@
+function main() {
+    let owner = address();
+}

compiler/tests/address/mod.rs

@@ -20,6 +20,14 @@ fn test_invalid() {
     let _output = expect_compiler_error(program);
 }
 
+#[test]
+fn test_empty() {
+    let bytes = include_bytes!("empty.leo");
+    let syntax_error = parse_program(bytes).is_err();
+
+    assert!(syntax_error);
+}
+
 #[test]
 fn test_implicit_valid() {
     let bytes = include_bytes!("implicit_valid.leo");