Add a check to ensure that Extend is extending a recognized type.

1 files changed, 4 insertions, 1 deletions

diff --git a/src/compile.c b/src/compile.c
index bd963951..89cb667b 100644
--- a/src/compile.c
+++ b/src/compile.c
@@ -4383,7 +4383,10 @@ CORD compile_top_level_code(env_t *env, ast_t *ast)
     }
     case Extend: {
         DeclareMatch(extend, ast, Extend);
-        env_t *ns_env = namespace_env(env, extend->name);
+        binding_t *b = get_binding(env, extend->name);
+        if (!b)
+            code_err(ast, "'", extend->name, "' is not the name of any type I recognize.");
+        env_t *ns_env = Match(b->type, TypeInfoType)->env;
         env_t *extended = new(env_t);
         *extended = *ns_env;
         extended->locals = new(Table_t, .fallback=env->locals);