sol-cover: TypeError: this.removeListener is not a function

[mo-h8]

I'm attempting to use @0x/sol-coverage and I'm running into issues with tests not completing. These tests listen for events. I have added added a websocketSubProvider to provider used in truffle-config.js

Here is the terminal output:

Contract: Example (End to End tests)
    ✓ Test 1) (46ms)
    1) Test 2
TypeError: this.removeListener is not a function
    at Object.receipt (/usr/local/lib/node_modules/truffle/build/webpack:/packages/truffle-contract/lib/handlers.js:134:1)
    at Function.start (/usr/local/lib/node_modules/truffle/build/webpack:/packages/truffle-contract/lib/override.js:56:1)
    at <anonymous>
TypeError: this.removeListener is not a function
    at Object.receipt (/usr/local/lib/node_modules/truffle/build/webpack:/packages/truffle-contract/lib/handlers.js:134:1)
    at Function.start (/usr/local/lib/node_modules/truffle/build/webpack:/packages/truffle-contract/lib/override.js:56:1)
    at <anonymous>
/usr/local/lib/node_modules/truffle/node_modules/mocha/lib/runner.js:707
  err.uncaught = true;
               ^
TypeError: Cannot create property 'uncaught' on string 'abort({}). Build with -s ASSERTIONS=1 for more info.'
    at Runner.uncaught (/usr/local/lib/node_modules/truffle/node_modules/mocha/lib/runner.js:707:16)
    at process.uncaught (/usr/local/lib/node_modules/truffle/node_modules/mocha/lib/runner.js:821:10)
    at emitOne (events.js:116:13)
    at process.emit (events.js:211:7)
    at process.emit (/usr/local/lib/node_modules/truffle/build/webpack:/~/source-map-support/source-map-support.js:461:1)
    at processEmit [as emit] (/usr/local/lib/node_modules/truffle/build/webpack:/~/signal-exit/index.js:155:1)
    at process._fatalException (bootstrap_node.js:375:26)`

truffle-config.js:

const ProviderEngine = require("web3-provider-engine");
const RpcSubProvider = require("web3-provider-engine/subproviders/rpc.js");
const WebsocketSubprovider = require("web3-provider-engine/subproviders/websocket.js");
const { TruffleArtifactAdapter } = require('@0x/sol-trace');
const projectRoot = '.';
const solcVersion = '0.5.9';
const artifactAdapter = new TruffleArtifactAdapter(projectRoot, solcVersion);

const { CoverageSubprovider } = require("@0x/sol-coverage");
const defaultFromAddress = "0x5409ed021d9299bf6814279a6a1411a7e866a631"; // Some ethereum address with test funds
const coverageSubprovider = new CoverageSubprovider(artifactAdapter, defaultFromAddress);

const provider = new ProviderEngine();
provider.addProvider(new RpcSubProvider({rpcUrl: 'http://localhost:7545'}));
provider.addProvider(coverageSubprovider);
provider.addProvider(new WebsocketSubprovider({rpcUrl: 'ws://localhost:7545/ws'}));

provider.start(err => {
  if (err !== undefined) {
    console.log(err);
    process.exit(1);
  }
});

module.exports = {
  // See <http://truffleframework.com/docs/advanced/configuration>
  // to customize your Truffle configuration!
  networks: {
    development: {
      provider: function() {
        return provider;
      },
      network_id: "*", // Match any network id
      // websockets: true
    }
  },
  compilers: {
    solc: {
      version: "^0.5.9", 
    }
  }
};

[stale]

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