Improve error handling

[aleksanderbl29]

I would like to add more informative error messages with clear instructions on what to do or where to find your error.

Especially the error in #22 needs fixing

[aleksanderbl29]

When trying to reproduce #24 i get this error

> dst_get_data(table = 'FV22TOTA', VALRES='*', OMRÅDE='*', Tid='*')
Error in dst_get_data(table = "FV22TOTA", VALRES = "*", OMRÅDE = "*",  : 
  {"errorTypeCode":"REQUEST-LIMIT","message":"Forespørgslen på op mod 6.224.652 celler er over begrænsningen på 1.000.000 celler for denne filtype. Anvend BULK eller andet streaming format i stedet."}

Would be nice to extract the message and tell the user that they should use "bulk" format

[aleksanderbl29]

With 8cb79e5 we now properly parse the error message and returns it directly to the user in the language specified.

[aleksanderbl29]

When trying to reproduce #24 i get this error

> dst_get_data(table = 'FV22TOTA', VALRES='*', OMRÅDE='*', Tid='*')
Error in dst_get_data(table = "FV22TOTA", VALRES = "*", OMRÅDE = "*",  : 
  {"errorTypeCode":"REQUEST-LIMIT","message":"Forespørgslen på op mod 6.224.652 celler er over begrænsningen på 1.000.000 celler for denne filtype. Anvend BULK eller andet streaming format i stedet."}

Would be nice to extract the message and tell the user that they should use "bulk" format

This has now been fixed with 8cb79e5