Properly handle upstream API errors

[traines-source]

Currently just showing "Error 502: Failed requesting timetable data.".

HTTP 502 Connection not found (too far in the past) e.g. /journeys?departure=2022-09-19T08%3A00%3A00.000%2B02%3A00&from=692415&to=895914

{
	"isHafasError": true,
	"request": "{\"lang\":\"en\",\"svcReqL\":[{\"cfg\":{\"polyEnc\":\"GPA\",\"rtMode\":\"HYBRID\"},\"meth\":\"TripSearch\",\"req\":{\"getPasslist\":false,\"maxChg\":-1,\"minChgTime\":0,\"depLocL\":[{\"type\":\"S\",\"lid\":\"A=1@L=692415@\"}],\"viaLocL\":[],\"arrLocL\":[{\"type\":\"S\",\"lid\":\"A=1@L=895914@\"}],\"jnyFltrL\":[{\"type\":\"PROD\",\"mode\":\"INC\",\"value\":\"1023\"},{\"type\":\"META\",\"mode\":\"INC\",\"meta\":\"notBarrierfree\"}],\"gisFltrL\":[],\"getTariff\":false,\"ushrp\":true,\"getPT\":true,\"getIV\":false,\"getPolyline\":false,\"outDate\":\"20220919\",\"outTime\":\"080000\",\"outFrwd\":true,\"trfReq\":{\"jnyCl\":2,\"tvlrProf\":[{\"type\":\"E\",\"redtnCard\":null}],\"cType\":\"PK\"}}}],\"client\":{\"type\":\"AND\",\"id\":\"DB\",\"v\":21120000,\"name\":\"DB Navigator\"},\"ext\":\"DB.R21.12.a\",\"ver\":\"1.34\",\"auth\":{\"type\":\"AID\",\"aid\":\"n91dB8Z77MLdoR0K\"}}",
	"url": "https://reiseauskunft.bahn.de/bin/mgate.exe?checksum=3cfb0da25d0e81e49aa943346f120265",
	"statusCode": 404,
	"isClient": true,
	"code": "NOT_FOUND",
	"message": "journeys search unsuccessful",
	"hafasErrorCode": "H890",
	"hafasErrorMessage": "HAFAS Kernel: No connection found",
	"error": true,
	"msg": "HAFAS error: journeys search unsuccessful"
}

HTTP 502 Date outside timetable period e.g. /journeys?departure=2022-12-17T06%3A30%3A00.000%2B01%3A00&from=8000244&to=8702383

{
	"isHafasError": true,
	"request": "{\"lang\":\"en\",\"svcReqL\":[{\"cfg\":{\"polyEnc\":\"GPA\",\"rtMode\":\"HYBRID\"},\"meth\":\"TripSearch\",\"req\":{\"getPasslist\":false,\"maxChg\":-1,\"minChgTime\":0,\"depLocL\":[{\"type\":\"S\",\"lid\":\"A=1@L=8000244@\"}],\"viaLocL\":[],\"arrLocL\":[{\"type\":\"S\",\"lid\":\"A=1@L=8702383@\"}],\"jnyFltrL\":[{\"type\":\"PROD\",\"mode\":\"INC\",\"value\":\"1023\"},{\"type\":\"META\",\"mode\":\"INC\",\"meta\":\"notBarrierfree\"}],\"gisFltrL\":[],\"getTariff\":false,\"ushrp\":true,\"getPT\":true,\"getIV\":false,\"getPolyline\":false,\"outDate\":\"20221217\",\"outTime\":\"063000\",\"outFrwd\":true,\"trfReq\":{\"jnyCl\":2,\"tvlrProf\":[{\"type\":\"E\",\"redtnCard\":null}],\"cType\":\"PK\"}}}],\"client\":{\"type\":\"AND\",\"id\":\"DB\",\"v\":21120000,\"name\":\"DB Navigator\"},\"ext\":\"DB.R21.12.a\",\"ver\":\"1.34\",\"auth\":{\"type\":\"AID\",\"aid\":\"n91dB8Z77MLdoR0K\"}}",
	"url": "https://reiseauskunft.bahn.de/bin/mgate.exe?checksum=8186ee987934e7f8a2f9cd5d207c97ae",
	"statusCode": 400,
	"isClient": true,
	"code": "INVALID_REQUEST",
	"message": "journeys search: invalid date/time",
	"hafasErrorCode": "H9360",
	"hafasErrorMessage": "HAFAS Kernel: Date outside of the timetable period.",
	"error": true,
	"msg": "HAFAS error: journeys search: invalid date/time"
}