add token instance metadata check

[ayrat555]

some token instances return integers as metadata

Motivation

fixes

2019-11-19T09:35:55.538 [error] Task #PID<0.20704.5> started from Indexer.Fetcher.TokenInstance terminating
** (MatchError) no match of right hand side value: {:error, #Ecto.Changeset<action: :insert, changes: %{token_contract_address_hash: %Explorer.Chain.Hash{byte_count: 20, bytes: <<104, 35, 202, 192, 134, 199, 8, 88, 185, 190, 194, 23, 112, 82, 10, 103, 36, 129, 169, 107>>}, token_id: #Decimal<3>}, errors: [metadata: {"is invalid", [type: :map, validation: :cast]}], data: #Explorer.Chain.Token.Instance<>, valid?: false>}
    (indexer) lib/indexer/fetcher/token_instance.ex:63: Indexer.Fetcher.TokenInstance.run/2
    (elixir) lib/task/supervised.ex:90: Task.Supervised.invoke_mfa/2
    (elixir) lib/task/supervised.ex:35: Task.Supervised.reply/5
    (stdlib) proc_lib.erl:249: :proc_lib.init_p_do_apply/3
Function: &Indexer.BufferedTask.log_run/1
    Args: [%{batch: [%{contract_address_hash: %Explorer.Chain.Hash{byte_count: 20, bytes: <<104, 35, 202, 192, 134, 199, 8, 88, 185, 190, 194, 23, 112, 82, 10, 103, 36, 129, 169, 107>>}, token_id: #Decimal<3>}], callback_module: Indexer.Fetcher.TokenInstance, callback_module_state: [transport: EthereumJSONRPC.HTTP, transport_options: [http: EthereumJSONRPC.HTTP.HTTPoison, url: "http://10.1.0.74:8545", method_to_url: [eth_getBalance: "http://10.1.0.74:8545", trace_block: "http://10.1.0.74:8545", trace_replayTransaction: "http://10.1.0.74:8545"], http_options: [recv_timeout: 600000, timeout: 600000, hackney: [pool: :ethereum_jsonrpc]]], variant: EthereumJSONRPC.Parity], metadata: []}]

Changelog

• add token instance metadata check

[coveralls]

Pull Request Test Coverage Report for Build fe81e1fd-d7ae-465b-99d4-801fe509e7db

• 1 of 1 (100.0%) changed or added relevant line in 1 file are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.004%) to 75.322%

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Totals
Change from base Build 324d81e6-beb6-4fa3-a8d4-c5f2723c2611:	0.004%
Covered Lines:	5259
Relevant Lines:	6982

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💛 - Coveralls

[vbaranov]

@ayrat555 no CHANGELOG entry