title: Chainlink VRF : Error encoding arguments: Error: invalid BigNumber string
body: <p>I'm trying to get a random number with Chainlink VRF,
  So Hi have follow this demo step by step : <a href="https://www.youtube.com/watch?v=JqZWariqh5s" rel="nofollow noreferrer">https://www.youtube.com/watch?v=JqZWariqh5s</a></p>
  <p>here is what i've copied on Remix :</p>
  <pre><code>pragma solidity 0.6.6;
  
  import &quot;https://raw.githubusercontent.com/smartcontractkit/chainlink/master/evm-contracts/src/v0.6/VRFConsumerBase.sol&quot;;
  
  contract RandomNumberConsumer is VRFConsumerBase {
      
      bytes32 public keyHash;
      uint256 public fee;
      uint256 public randomResult;
      
      constructor() VRFConsumerBase(
              0xdD3782915140c8f3b190B5D67eAc6dc5760C46E9, // VRF Coordinator
              0xa36085F69e2889c224210F603D836748e7dC0088  // LINK Token
          ) public
      {
          keyHash = 0x6c3699283bda56ad74f6b855546325b68d482e983852a7a82979cc4807b641f4;
          fee = 0.1 * 10 ** 18; // 0.1 LINK
      }
      
  
      function getRandomNumber(uint256 userProvidedSeed) public returns (bytes32 requestId) {
          return requestRandomness(keyHash, fee, userProvidedSeed);
      }
  
      function fulfillRandomness(bytes32 requestId, uint256 randomness) internal override {
          randomResult = randomness.mod(50).add(1);
      }
  }
  </code></pre>
  <p>when i click on <em>getRandomNumber</em>, i always get this error :
  <strong>Error encoding arguments: Error: invalid BigNumber string (argument=&quot;value&quot;, value=&quot;&quot;, code=INVALID_ARGUMENT, version=bignumber/5.0.8)</strong></p>
  <p>and with the <em>fulfillRandomness</em>, i get this error :
  <strong>Error encoding arguments: Error: invalid arrayify value (argument=&quot;value&quot;, value=&quot;&quot;, code=INVALID_ARGUMENT, version=bytes/5.0.5)</strong></p>