[pygobject/pygobject-3-32] pygi_error_marshal_to_py: Fix error return handling. Fixes #315

[Christoph Reiter <creiter src gnome org>]

commit f4043503065d73bdf75839e83cfbcfd4b124b606
Author: Christoph Reiter <reiter christoph gmail com>
Date:   Sun Mar 24 09:14:43 2019 +0100

    pygi_error_marshal_to_py: Fix error return handling. Fixes #315
    
    It returned NULL in case no error was set or if creating the error
    result failed and this wasn't checked by the callers.
    
    Change it to return Py_None in case no error was set and NULL in
    case of an error. In pygi_error_check() we can't really forward the
    error, so just print it and raise RuntimeError instead.

 gi/pygi-error.c | 27 +++++++++++++--------------
 1 file changed, 13 insertions(+), 14 deletions(-)
---
diff --git a/gi/pygi-error.c b/gi/pygi-error.c
index 8e4a7934..b0eeccd1 100644
--- a/gi/pygi-error.c
+++ b/gi/pygi-error.c
@@ -36,8 +36,10 @@ PyObject *PyGError = NULL;
  *
  * Checks to see if @error has been set.  If @error has been set, then a
  * GLib.GError Python exception object is returned (but not raised).
+ * If not error is set returns Py_None.
  *
- * Returns: a GLib.GError Python exception object, or NULL.
+ * Returns: a GLib.GError Python exception object, or Py_None,
+ *     or NULL and sets an error if creating the exception object fails.
  */
 PyObject *
 pygi_error_marshal_to_py (GError **error)
@@ -50,7 +52,7 @@ pygi_error_marshal_to_py (GError **error)
     g_return_val_if_fail(error != NULL, NULL);
 
     if (*error == NULL)
-        return NULL;
+        Py_RETURN_NONE;
 
     state = PyGILState_Ensure();
 
@@ -93,8 +95,13 @@ pygi_error_check (GError **error)
     state = PyGILState_Ensure();
 
     exc_instance = pygi_error_marshal_to_py (error);
-    PyErr_SetObject(PyGError, exc_instance);
-    Py_DECREF(exc_instance);
+    if (exc_instance != NULL) {
+        PyErr_SetObject(PyGError, exc_instance);
+        Py_DECREF(exc_instance);
+    } else {
+        PyErr_Print ();
+        PyErr_SetString (PyExc_RuntimeError, "Converting the GError failed");
+    }
     g_clear_error(error);
 
     PyGILState_Release(state);
@@ -266,11 +273,7 @@ _pygi_marshal_to_py_gerror (PyGIInvokeState   *state,
         g_error_free (error);
     }
 
-    if (py_obj != NULL) {
-        return py_obj;
-    } else {
-        Py_RETURN_NONE;
-    }
+    return py_obj;
 }
 
 static gboolean
@@ -330,11 +333,7 @@ pygerror_from_gvalue (const GValue *value)
 {
     GError *gerror = (GError *) g_value_get_boxed (value);
     PyObject *pyerr = pygi_error_marshal_to_py (&gerror);
-    if (pyerr == NULL) {
-        Py_RETURN_NONE;
-    } else {
-        return pyerr;
-    }
+    return pyerr;
 }
 
 static int