(Please note: Exlir/Poison Experience Level: Beginner so please Eli5)

Given:

iex(1)> results = HTTPoison.get!("https://nodes.wavesnodes.com/assets/balance/3PDh3tDWWXmJtfoqRkf1p9PnZAHmBLcWXFW")
%HTTPoison.Response{
  body: "{\"address\":\"3PDh3tDWWXmJtfoqRkf1p9PnZAHmBLcWXFW\",\"balances\":[{\"assetId\":\"6GQkwHGyd769EghKQ6qXhAHG55JyaFjK7VGWEKSSg4Z8\",\"balance\":100000000,\"reissuable\":false,\"minSponsoredAssetFee\":null,\"sponsorBalance\":null,\"quantity\":2099443248805633,\"issueTransaction\":{\"senderPublicKey\":\"2TW1p199hYspTxt3hZc2wm9VGGDE4qFxyY2Th1HoFVww\",\"quantity\":2100000000000000,\"fee\":100000000,\"description\":\"\\\"Progression\\\" conception intelligente de jeton innovant qui se limite à évaluer 0,0001 de vagues par jour, les commandes sont limitées à 100 minutes pour stimuler la progression quotidienne.\\n\\\"Progression\\\" innovative token intelligent design that is limited to valuing 0.0001 of waves per day, orders are limited to 100 minutes to stimulate daily progression.\",\"type\":3,\"version\":2,\"reissuable\":false,\"script\":\"base64: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\",\"sender\":\"3PMQ27yBjrshdxGmFjTZHY6taN17saQyfM8\",\"feeAssetId\":null,\"chainId\":87,\"proofs\":[\"2YAgh7QQ49oFqgTfDYT5mh58xcqspR2kQJrpiLYRTtyPrtakUuYjVyt9ejr5m3suF7FZUhze1ZmXU1Ry6yJdWheV\"],\"assetId\":\"6GQkwHGyd769EghKQ6qXhAHG55JyaFjK7VGWEKSSg4Z8\",\"decimals\":8,\"name\":\"Progression\",\"id\":\"6GQkwHGyd769EghKQ6qXhAHG55JyaFjK7VGWEKSSg4Z8\",\"timestamp\":1550319832173}},{\"assetId\":\"51LxAtwBXapvvTFSbbh4nLyWFxH6x8ocfNvrXxbTChze\",\"balance\":6,\"reissuable\":false,\"minSponsoredAssetFee\":10000,\"sponsorBalance\":90323001,\"quantity\":9999999886689962,\"issueTransaction\":{\"senderPublicKey\":\"FCfKDQiCaNruTAj984WCrQLHS1j1c8Fv5JzgKswgAhoy\",\"quantity\":10000000000000000,\"fee\":100000000,\"description\":\"TOR Corporation\\nОфициальная чат-группа монет TOR https://t.me/projecttorcoin \\nWhite paper https://docs.google.com/document/d/1LJfo6X82cAjLI4tahkVN-jR_GU8a4d2aZ_tFtXP4yYI/edit?usp=sharing Дорожная карта https://docs.google.com/document/d/1qBheIvDO3KSfyQnWQdbwUBKZtalaILhCak03fJlQRTk/edit?usp=sharing\",\"type\":3,\"version\":2,\"reissuable\":false,\"script\":null,\"sender\":\"3P287ZEpVU14SAr4jhCF58fZPzfkQv4LXqm\",\"feeAssetId\":null,\"chainId\":87,\"proofs\":[\"4f7ZzQ5ZgZskxnCDhU4RKx6MWCHNVrnJs8hKRfGWX35aSyJtcJqrQuUaahrqcAnYU8dpDq8rRUvTtwa6VhcEEx7v\"],\"assetId\":\"51LxAtwBXapvvTFSbbh4nLyWFxH6x8ocfNvrXxbTChze\",\"decimals\":6,\"name\":\"TORCorp\",\"id\":\"51LxAtwBXapvvTFSbbh4nLyWFxH6x8ocfNvrXxbTChze\",\"timestamp\":1541398865252}},{\"assetId\":\"GAAZu8fsWfrZBFgweMMAFEcjrW9CFRxPEqmGcbSGWVDF\",\"balance\":300000000,\"reissuable\":false,\"minSponsoredAssetFee\":null,\"sponsorBalance\":null,\"quantity\":4999999200000000,\"issueTransaction\":{\"senderPublicKey\":\"jYTtcsLgDD5NcoDHUAnHLdC9PjeSwyjxFysptotgHjq\",\"quantity\":10000000000000000,\"fee\":100000000,\"description\":\"K975 Token\",\"type\":3,\"version\":2,\"reissuable\":false,\"script\":null,\"sender\":\"3PMSXKE9AqLMw2Yh5nTscm2DSJP677hf2QJ\",\"feeAssetId\":null,\"chainId\":87,\"proofs\":[\"2GPLuTFZFb8bLKV1AJ15VUtjHpmMcvXo8nNmi9F5pwdptgudiGXwU2efM5BFCP2FvK7zAdR5zQPBguJFY4kyUqXd\"],\"assetId\":\"GAAZu8fsWfrZBFgweMMAFEcjrW9CFRxPEqmGcbSGWVDF\",\"decimals\":8,\"name\":\"K975\",\"id\":\"GAAZu8fsWfrZBFgweMMAFEcjrW9CFRxPEqmGcbSGWVDF\",\"timestamp\":1568118516242}},{\"assetId\":\"2rdZt8RxEftbmz34HLBd7Au2icyScgAe5YoipeT7GwK2\",\"balance\":1,\"reissuable\":false,\"minSponsoredAssetFee\":null,\"sponsorBalance\":null,\"quantity\":49999986,\"issueTransaction\":{\"senderPublicKey\":\"StYAY98BDsSDvhMRFauKxn5pWEcD6KxnRnvPDbtceZ" <> ...,
  headers: [
    {"Date", "Sat, 12 Oct 2019 20:01:32 GMT"},
    {"Content-Type", "application/json"}, 
    {"Transfer-Encoding", "chunked"},
    {"Connection", "keep-alive"},
    {"Set-Cookie",
     "__cfduid=d7522b5d559f3952392299b4e3c07a2cb1570910492; expires=Sun, 11-Oct-20 20:01:32 GMT; path=/; domain=.wavesnodes.com; HttpOnly"}, 
    {"Vary", "Accept-Encoding"},
    {"Access-Control-Allow-Origin", "*"},
    {"Access-Control-Allow-Credentials", "true"},
    {"Access-Control-Allow-Methods", "GET, POST, OPTIONS, PUT, DELETE"},
    {"Access-Control-Allow-Headers",
     "DNT,User-Agent,X-Requested-With,If-Modified-Since,Cache-Control,Content-Type,Range,signature,timestamp"},
    {"Access-Control-Expose-Headers", "Content-Length,Content-Range"},
    {"Backend", "ca-2"},
    {"Content-Security-Policy",
     "default-src 'self'; script-src 'self' 'unsafe-inline'; style-src 'self' 'unsafe-inline'; img-src 'self' online.swagger.io"},
    {"X-Frame-Options", "DENY"},
    {"X-XSS-Protection", "0"},
    {"X-Content-Type-Options", "nosniff"},
    {"Referrer-Policy", "unsafe-url"},
    {"CF-Cache-Status", "DYNAMIC"},
    {"Set-Cookie",
     "AWSALB=3/o7aRqBwecPhGPjflqgWoA5R8nviB4AuiJ+hzmjke8QIkv4rXRCeAGXxGHYs4OTYS+C/EfEUc83sWOSdFdpDe7ugPrSkX3GqeX4+BBNCnpy510HP/sehtLLBkim; Expires=Sat, 19 Oct 2019 20:01:32 GMT; Path=/"},
    {"Set-Cookie",
     "__cflb=3256034178; path=/; expires=Sun, 13-Oct-19 19:01:32 GMT; HttpOnly"},
    {"Expect-CT",
     "max-age=604800, report-uri=\"https://report-uri.cloudflare.com/cdn-cgi/beacon/expect-ct\""},
    {"Server", "cloudflare"},
    {"CF-RAY", "524baa8f68e9c7c5-DEN"}
  ],
  request: %HTTPoison.Request{
    body: "",
    headers: [], 
    method: :get,
    options: [],
    params: %{},
    url: "https://nodes.wavesnodes.com/assets/balance/3PDh3tDWWXmJtfoqRkf1p9PnZAHmBLcWXFW"
  },
  request_url: "https://nodes.wavesnodes.com/assets/balance/3PDh3tDWWXmJtfoqRkf1p9PnZAHmBLcWXFW",
  status_code: 200
}

Why does this fail?

iex(2)> %{data: items} = Poison.decode!(results.body, keys: :atoms)
** (MatchError) no match of right hand side value: %{address: "3PDh3tDWWXmJtfoqRkf1p9PnZAHmBLcWXFW", balances: [%{assetId: "6GQkwHGyd769EghKQ6qXhAHG55JyaFjK7VGWEKSSg4Z8", balance: 100000000, issueTransaction: %{assetId: "6GQkwHGyd769EghKQ6qXhAHG55JyaFjK7VGWEKSSg4Z8", chainId: 87, decimals: 8, description: "\"Progression\" conception intelligente de jeton innovant qui se limite à évaluer 0,0001 de vagues par jour, les commandes sont limitées à 100 minutes pour stimuler la progression quotidienne.\n\"Progression\" innovative token intelligent design that is limited to valuing 0.0001 of waves per day, orders are limited to 100 minutes to stimulate daily progression.", fee: 100000000, feeAssetId: nil, id: "6GQkwHGyd769EghKQ6qXhAHG55JyaFjK7VGWEKSSg4Z8", name: "Progression", proofs: ["2YAgh7QQ49oFqgTfDYT5mh58xcqspR2kQJrpiLYRTtyPrtakUuYjVyt9ejr5m3suF7FZUhze1ZmXU1Ry6yJdWheV"], quantity: 2100000000000000, reissuable: false, script: "base64: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", sender: "3PMQ27yBjrshdxGmFjTZHY6taN17saQyfM8", senderPublicKey: "2TW1p199hYspTxt3hZc2wm9VGGDE4qFxyY2Th1HoFVww", timestamp: 1550319832173, type: 3, version: 2}, minSponsoredAssetFee: nil, quantity: 2099443248805633, reissuable: false, sponsorBalance: nil}, }
    (stdlib) erl_eval.erl:453: :erl_eval.expr/5
    (iex) lib/iex/evaluator.ex:257: IEx.Evaluator.handle_eval/5
    (iex) lib/iex/evaluator.ex:237: IEx.Evaluator.do_eval/3
    (iex) lib/iex/evaluator.ex:215: IEx.Evaluator.eval/3
    (iex) lib/iex/evaluator.ex:103: IEx.Evaluator.loop/1
    (iex) lib/iex/evaluator.ex:27: IEx.Evaluator.init/4