decoder.c: Fix a scan-build warning.

  decoder.c:343:9: warning: Access to field 'ob_type' results in a dereference of a null pointer (loaded from variable 'py_default')
                                  if (Py_TYPE(py_default) != Py_TYPE(py_item)) {
                                      ^~~~~~~~~~~~~~~~~~~
  /usr/include/python3.6m/object.h:118:33: note: expanded from macro 'Py_TYPE'
  #define Py_TYPE(ob)             (((PyObject*)(ob))->ob_type)
                                  ^~~~~~~~~~~~~~~~~~~~~~~~~~~~

1 files changed, 1 insertions, 1 deletions

diff --git a/decoder.c b/decoder.c
index 21b756b..bebe96c 100644
--- a/decoder.c
+++ b/decoder.c
@@ -340,7 +340,7 @@ static int get_options(struct srd_decoder *d)
 				if (!py_item)
 					goto except_out;
 
-				if (Py_TYPE(py_default) != Py_TYPE(py_item)) {
+				if (py_default && (Py_TYPE(py_default) != Py_TYPE(py_item))) {
 					srd_err("All values for option '%s' must be "
 						"of the same type as the default.",
 						o->id);