Clean up final types in the case of an error

Make sure we clean up finals if we run into an error while running the
initialization code.

Author: pranavrajpal

mypyc/codegen/emitmodule.py

@@ -36,7 +36,7 @@
     generate_legacy_wrapper_function, legacy_wrapper_function_header,
 )
 from mypyc.ir.ops import DeserMaps, LoadLiteral
-from mypyc.ir.rtypes import RType, RTuple
+from mypyc.ir.rtypes import RType, RTuple, is_tagged
 from mypyc.ir.func_ir import FuncIR
 from mypyc.ir.class_ir import ClassIR
 from mypyc.ir.module_ir import ModuleIR, ModuleIRs, deserialize_modules
@@ -925,6 +925,12 @@ def generate_module_def(self, emitter: Emitter, module_name: str, module: Module
                            'Py_XDECREF(modname);')
         # the type objects returned from CPyType_FromTemplate are all new references
         # so we have to decref them
+        for name, typ in module.final_names:
+            static_name = emitter.static_name(name, module_name)
+            if emitter.ctype(typ) == 'PyObject *':
+                emitter.emit_line('Py_CLEAR({});'.format(static_name))
+            elif is_tagged(typ):
+                emitter.emit_line('CPyTagged_XDecRef({});'.format(static_name))
         for t in type_structs:
             emitter.emit_line('Py_XDECREF({});'.format(t))
         emitter.emit_line('return NULL;')