Provide more descriptive messages from decoding errors.

[tachyonics]

Issue #, if available:

Description of changes: Provide more descriptive messages from decoding errors rather than just providing the raw Swift error structure-

{
  "__type" : "DecodingError",
  "message" : "No value associated with key CodingKeys(stringValue: \"theAttribute\", intValue: nil) (\"theAttribute\")."
}

Instead

{
  "__type" : "DecodingError",
  "message" : "Key not found at path 'theAttribute'."
}

{
  "__type" : "DecodingError",
  "message" : "Required value not found at path 'container.theAttribute'."
}

{
  "__type" : "DecodingError",
  "message" : "Data corrupted at path 'regions[1]'. Cannot initialize Region from invalid String value HAHA."
}

{
  "__type" : "DecodingError",
  "message" : "Incorrect type at path 'theAttribute'. Expected String."
}

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