+/* Returns an ovsdb_error that represents an internal error for file name
+ * 'file' and line number 'line', with 'details' (formatted as with printf())
+ * as the associated message. The caller is responsible for freeing the
+ * returned error.
+ *
+ * If 'inner_error' is nonnull then the returned error is wrapped around
+ * 'inner_error'. Takes ownership of 'inner_error'. */