Return invalid statement if namespace is not followed by an identifier.

src/parsing/parser/mod.rs

@@ -112,6 +112,7 @@ fn parse_namespace(
                 },
                 identifier_token.span,
             );
+            return Box::new(ParsedStatement::Invalid);
         }
     }
     reader.consume(TokenType::OpenCurlyBracket, log);

src/parsing/parser/parsed_statement.rs

@@ -1,5 +1,5 @@
 pub enum ParsedStatement {
+    Invalid,
     Script(Vec<Box<ParsedStatement>>),
     Namespace(String, Box<ParsedStatement>),
-    
 }