chore: fix flow linting

web3.js/.eslintrc.js

@@ -8,12 +8,14 @@ module.exports = {
     'eslint:recommended',
     'plugin:import/errors',
     'plugin:import/warnings',
+    'plugin:flowtype/recommended',
   ],
   parser: 'babel-eslint',
   parserOptions: {
     sourceType: 'module',
     ecmaVersion: 8,
   },
+  plugins: ['flowtype'],
   rules: {
     'no-trailing-spaces': ['error'],
     'import/first': ['error'],
@@ -45,6 +47,7 @@ module.exports = {
     ],
     'require-await': ['error'],
     semi: ['error', 'always'],
+    'flowtype/generic-spacing': [0],
   },
 
   // Used to lint the TypeScript type declaration file

web3.js/package-lock.json

@@ -9550,6 +9550,15 @@
         "pkg-dir": "^2.0.0"
       }
     },
+    "eslint-plugin-flowtype": {
+      "version": "4.6.0",
+      "resolved": "https://registry.npmjs.org/eslint-plugin-flowtype/-/eslint-plugin-flowtype-4.6.0.tgz",
+      "integrity": "sha512-W5hLjpFfZyZsXfo5anlu7HM970JBDqbEshAJUkeczP6BFCIfJXuiIBQXyberLRtOStT0OGPF8efeTbxlHk4LpQ==",
+      "dev": true,
+      "requires": {
+        "lodash": "^4.17.15"
+      }
+    },
     "eslint-plugin-import": {
       "version": "2.20.1",
       "resolved": "https://registry.npmjs.org/eslint-plugin-import/-/eslint-plugin-import-2.20.1.tgz",

web3.js/package.json

@@ -107,6 +107,7 @@
     "esdoc-standard-plugin": "^1.0.0",
     "eslint": "6.8.0",
     "eslint-config-prettier": "^6.0.0",
+    "eslint-plugin-flowtype": "^4.6.0",
     "eslint-plugin-import": "2.20.1",
     "eslint-plugin-jest": "22.19.0",
     "eslint-plugin-prettier": "^3.0.0",

web3.js/test/__mocks__/rpc-websockets.js

@@ -1,3 +1,5 @@
+// @flow
+
 import {Client as RpcWebSocketClient} from 'rpc-websockets';
 
 // Define TEST_LIVE in the environment to test against the real full node