function _getMessagesFromXHR(oXHR) {
		var aMessages = [];

		try {
			var oErrorResponse = JSON.parse(oXHR.responseText);
			if (oErrorResponse && oErrorResponse.error && oErrorResponse.error.message && oErrorResponse.error.message.value) {
				aMessages.push({
					severity: "error",
					text: oErrorResponse.error.message.value
				});
			} else {
				aMessages.push({
					severity: "error",
					text: oXHR.responseText
				});
			}
		} catch (e) {
			// ignore
		}

		return aMessages;
	}
Extracts error messages from request failure response

@private
@param {object} oXHR - request object
@returns {array} errorMessages