Collada(exporter): Added error message when export file can not be created for whichever reason

source/blender/collada/collada.cpp

@@ -76,6 +76,7 @@ int collada_export(Scene *sce,
 	if (!BLI_exists(filepath)) {
 		BLI_make_existing_file(filepath);     /* makes the dir if its not there */
 		if (BLI_file_touch(filepath) == 0) {
+			fprintf(stdout, "Collada export: Can not create: %s\n", filepath);
 			return 0;
 		}
 	}

source/blender/editors/io/io_collada.c

@@ -143,6 +143,7 @@ static int wm_collada_export_exec(bContext *C, wmOperator *op)
 		return OPERATOR_FINISHED;
 	}
 	else {
+		BKE_report(op->reports, RPT_WARNING, "Export file not created.");
 		return OPERATOR_CANCELLED;
 	}
 }