[processing] fixed issue with saga optimizations

Author: volaya

python/plugins/processing/core/GeoAlgorithm.py

@@ -171,7 +171,7 @@ def execute(self, progress, model = None):
                 lines.append(errstring)
             lines.append(errstring.replace("\n", "|"))
             ProcessingLog.addToLog(ProcessingLog.LOG_ERROR, lines)
-            raise GeoAlgorithmExecutionException(str(e))
+            raise GeoAlgorithmExecutionException(str(e) + "\nSee log for more details")
 
 
     def runPostExecutionScript(self, progress):

python/plugins/processing/saga/SagaAlgorithm.py

@@ -229,7 +229,9 @@ def processAlgorithm(self, progress):
                 if param.datatype == ParameterMultipleInput.TYPE_RASTER:
                     for layerfile in layers:
                         if not layerfile.endswith("sgrd"):
-                            commands.append(self.exportRasterLayer(layerfile))
+                            exportCommand = self.exportRasterLayer(layerfile)
+                            if exportCommand is not None:
+                                commands.append()
                         if self.resample:
                             commands.append(self.resampleRasterLayer(layerfile));
                 elif param.datatype == ParameterMultipleInput.TYPE_VECTOR_ANY: