cinterion: check error returned by g_task_propagate_error instead

When returning an enum value via g_task_return_int, some code assumes
the enum value is always non-negative and thus considers that a negative
value implies an error. This assumption could be invalidated if a
negative value is later added to the enum. To make it less error prone
to future changes, this patch modifies the code to check if the GError
argument to g_task_propagate_error is populated instead.

plugins/cinterion/mm-broadband-bearer-cinterion.c

@@ -85,10 +85,15 @@ load_connection_status_finish (MMBaseBearer  *bearer,
                                GAsyncResult  *res,
                                GError       **error)
 {
+    GError *inner_error = NULL;
     gssize aux;
 
-    aux = g_task_propagate_int (G_TASK (res), error);
-    return (aux < 0 ? MM_BEARER_CONNECTION_STATUS_UNKNOWN : (MMBearerConnectionStatus) aux);
+    aux = g_task_propagate_int (G_TASK (res), &inner_error);
+    if (inner_error) {
+        g_propagate_error (error, inner_error);
+        return MM_BEARER_CONNECTION_STATUS_UNKNOWN;
+    }
+    return (MMBearerConnectionStatus) aux;
 }
 
 static void

plugins/cinterion/mm-broadband-modem-cinterion.c

@@ -582,10 +582,14 @@ load_access_technologies_finish (MMIfaceModem             *self,
                                  guint                    *mask,
                                  GError                  **error)
 {
+    GError *inner_error = NULL;
     gssize val;
 
-    if ((val = g_task_propagate_int (G_TASK (res), error)) < 0)
+    val = g_task_propagate_int (G_TASK (res), &inner_error);
+    if (inner_error) {
+        g_propagate_error (error, inner_error);
         return FALSE;
+    }
 
     *access_technologies = (MMModemAccessTechnology) val;
     *mask = MM_MODEM_ACCESS_TECHNOLOGY_ANY;

plugins/cinterion/mm-common-cinterion.c

@@ -122,11 +122,14 @@ mm_common_cinterion_location_load_capabilities_finish (MMIfaceModemLocation  *se
                                                        GAsyncResult          *res,
                                                        GError               **error)
 {
+    GError *inner_error = NULL;
     gssize aux;
 
-    if ((aux = g_task_propagate_int (G_TASK (res), error)) < 0)
+    aux = g_task_propagate_int (G_TASK (res), &inner_error);
+    if (inner_error) {
+        g_propagate_error (error, inner_error);
         return MM_MODEM_LOCATION_SOURCE_NONE;
-
+    }
     return (MMModemLocationSource) aux;
 }