message: null Array decoding
diff: @@ -8,7 +8,14 @@ import u8aToBn from '@polkadot/util/u8a/toBn';
  import decodeValue from './value';
  -function decodeTuple (type: Param$Type$Array, input: Uint8Array, version: EncodingVersions): Param$Decoded {
  +function decodeTuple (type: Param$Type$Array, input: Uint8Array | null, version: EncodingVersions): Param$Decoded {
  + if (!input) {
  + return {
  + length: 0,
  + value: []
  + };
  + }
  +
  const value: Param$Value$Array = [];
  let length = 0;
  @@ -26,7 +33,14 @@ function decodeTuple (type: Param$Type$Array, input: Uint8Array, version: Encodi
  };
  }
  -function decodeArray ([ type ]: Param$Type$Array, input: Uint8Array, version: EncodingVersions): Param$Decoded {
  +function decodeArray ([ type ]: Param$Type$Array, input: Uint8Array | null, version: EncodingVersions): Param$Decoded {
  + if (!input) {
  + return {
  + length: 0,
  + value: []
  + };
  + }
  +
  const arrayLength = u8aToBn(input.subarray(0, 4), true).toNumber();
  const value: Param$Value$Array = [];
  let length = 4;
  