message: tx_invalid test case: Fix uninitialized variable
  (from clang static analysis)
diff: @@ -140,7 +140,7 @@ BOOST_AUTO_TEST_CASE(tx_invalid)
  UniValue tests =
  read_json(std::string(json_tests::tx_invalid, json_tests::tx_invalid + sizeof(json_tests::tx_invalid)));
  - ScriptError err;
  + ScriptError err = SCRIPT_ERR_OK;
  for (unsigned int idx = 0; idx < tests.size(); idx++)
  {
  UniValue test = tests[idx];
  