Update eslint and eslint configuration

This commit updates eslint from v4 to v6. In doing so, I've moved off of
the create-react-app base eslint config. We were on an old version (v2)
and it doesn't make sense to update to v4, as in v4 create-react-app
uses typescript. Also, it didn't make sense to stay on
create-react-app's v2 config, because then it had unmet peer dependency
constraints on old versions of eslint.

Instead, I've moved us to use the default rules for eslint,
eslint-plugin-react, and eslint-plugin-flowtype.

I also made some changes to the codebase to satisfy the new lint rules
that came with this change.

Test plan: `yarn test` passes.

.eslintrc.js

@@ -1,8 +1,25 @@
 // @flow
 module.exports = {
   parser: "babel-eslint",
-  plugins: ["flowtype"],
-  extends: "react-app",
+  plugins: ["flowtype", "react"],
+  env: {
+    browser: true,
+    es6: true,
+    node: true,
+    jest: true,
+  },
+  parserOptions: {
+    ecmaVersion: 2018,
+    sourceType: "module",
+    ecmaFeatures: {
+      jsx: true,
+    },
+  },
+  extends: [
+    "eslint:recommended",
+    "plugin:react/recommended",
+    "plugin:flowtype/recommended",
+  ],
   rules: {
     "no-unused-vars": [
       "warn",
@@ -14,5 +31,14 @@ module.exports = {
     ],
     "no-use-before-define": ["off"],
     "no-useless-constructor": ["off"],
+    "no-case-declarations": ["off"],
+    "react/prop-types": ["off"],
+    "flowtype/generic-spacing": ["off"],
+    "flowtype/space-after-type-colon": ["off"],
+  },
+  settings: {
+    react: {
+      version: "detect",
+    },
   },
 };

package.json

@@ -32,7 +32,7 @@
   },
   "devDependencies": {
     "babel-core": "6.26.0",
-    "babel-eslint": "7.2.3",
+    "babel-eslint": "10.0.2",
     "babel-jest": "20.0.3",
     "babel-loader": "7.1.2",
     "babel-plugin-transform-es2015-for-of": "^6.23.0",
@@ -45,12 +45,12 @@
     "enzyme": "^3.3.0",
     "enzyme-adapter-react-16": "^1.1.1",
     "enzyme-to-json": "^3.3.3",
-    "eslint": "4.10.0",
+    "eslint": "6.0.1",
+    "eslint-plugin-flowtype": "3.11.1",
     "eslint-config-react-app": "^2.1.0",
-    "eslint-plugin-flowtype": "2.50.0",
-    "eslint-plugin-import": "2.8.0",
-    "eslint-plugin-jsx-a11y": "5.1.1",
-    "eslint-plugin-react": "7.4.0",
+    "eslint-plugin-import": "2.18.0",
+    "eslint-plugin-jsx-a11y": "6.2.3",
+    "eslint-plugin-react": "7.14.2",
     "file-loader": "1.1.5",
     "flow-bin": "^0.102.0",
     "jest": "^24.8.0",

src/core/address.test.js

@@ -55,7 +55,7 @@ describe("core/address", () => {
       const {FooAddress} = makeModules();
       expect(() => {
         // $ExpectFlowError
-        FooAddress.assertValid = FooAddress.assertValid;
+        FooAddress.assertValid = FooAddress.assertValid; // eslint-disable-line no-self-assign
       }).toThrow(/read.only property/);
     });
 

src/explorer/pagerankTable/TableRow.test.js

@@ -17,9 +17,10 @@ describe("explorer/pagerankTable/TableRow", () => {
         description={<span data-test-description={true} />}
         multiuseColumn={"50.00%"}
         cred={133.7}
-        children={<div data-test-children={true} />}
         showPadding={false}
-      />
+      >
+        <div data-test-children={true} />{" "}
+      </TableRow>
     );
   }
   it("depth parameter changes the color, but not the indentation", () => {
@@ -32,8 +33,9 @@ describe("explorer/pagerankTable/TableRow", () => {
           description={<span data-test-description={true} />}
           multiuseColumn={"50.00%"}
           cred={133.7}
-          children={<div data-test-children={true} />}
-        />
+        >
+          <div data-test-children={true} />
+        </TableRow>
       );
       const tr = el.find("tr");
       const trStyle = tr.props().style;
@@ -52,8 +54,9 @@ describe("explorer/pagerankTable/TableRow", () => {
           description={<span data-test-description={true} />}
           multiuseColumn={"50.00%"}
           cred={133.7}
-          children={<div data-test-children={true} />}
-        />
+        >
+          <div data-test-children={true} />
+        </TableRow>
       );
       const tr = el.find("tr");
       const trStyle = tr.props().style;
@@ -138,9 +141,10 @@ describe("explorer/pagerankTable/TableRow", () => {
           description={<span data-test-description={true} />}
           multiuseColumn={"50.00%"}
           cred={133.7}
-          children={<div data-test-children={true} />}
           showPadding={true}
-        />
+        >
+          <div data-test-children={true} />
+        </TableRow>
       );
     }
     it("has two identical padding rows", () => {

src/graphql/schema.js

@@ -84,6 +84,19 @@ export type NestedFieldType = {|
 const ID_FIELD_NAME = "id";
 
 export function schema(types: {[Typename]: NodeType}): Schema {
+  function assertKind(path, elementTypename, validKinds) {
+    const self = `field ${path.map((x) => JSON.stringify(x)).join("/")}`;
+    const elementType = types[elementTypename];
+    if (elementType == null) {
+      throw new Error(`${self} has unknown type: "${elementTypename}"`);
+    }
+    if (!validKinds.includes(elementType.type)) {
+      throw new Error(
+        `${self} has invalid type "${elementTypename}" ` +
+          `of kind "${elementType.type}"`
+      );
+    }
+  }
   const result = {};
   for (const typename of Object.keys(types)) {
     const type = types[typename];
@@ -100,21 +113,6 @@ export function schema(types: {[Typename]: NodeType}): Schema {
       case "OBJECT":
         for (const fieldname of Object.keys(type.fields)) {
           const field = type.fields[fieldname];
-          function assertKind(path, elementTypename, validKinds) {
-            const self = `field ${path
-              .map((x) => JSON.stringify(x))
-              .join("/")}`;
-            const elementType = types[elementTypename];
-            if (elementType == null) {
-              throw new Error(`${self} has unknown type: "${elementTypename}"`);
-            }
-            if (!validKinds.includes(elementType.type)) {
-              throw new Error(
-                `${self} has invalid type "${elementTypename}" ` +
-                  `of kind "${elementType.type}"`
-              );
-            }
-          }
           switch (field.type) {
             case "ID":
               // Nothing to check.

src/homepage/index.js

@@ -34,5 +34,5 @@ ReactDOM.hydrate(<App routeData={routeData} history={history} />, target);
 for (const el of document.querySelectorAll('link[rel="shortcut icon"]')) {
   const link: HTMLLinkElement = (el: any);
   // (Appearances aside, this is not a no-op.)
-  link.href = link.href;
+  link.href = link.href; // eslint-disable-line no-self-assign
 }

src/util/FileUploaderInspectionTest.js

@@ -44,7 +44,7 @@ export default class FileUploaderInspectionTest extends React.Component<
         {this.state.json ? (
           <pre style={{backgroundColor: "#efefef"}}>{displayContents}</pre>
         ) : (
-          <p>"No JSON uploaded."</p>
+          <p>{"No JSON uploaded."}</p>
         )}
       </div>
     );

src/webutil/Link.test.js

@@ -16,6 +16,7 @@ describe("webutil/Link", () => {
 
   // Static type checks
   void [
+    /* eslint-disable react/jsx-key */
     // Must specify either `href` or `to`
     <Link href="https://example.com/">click me</Link>,
     <Link to="/prototype/">click me, too</Link>,
@@ -27,6 +28,7 @@ describe("webutil/Link", () => {
 
     // May specify extra properties
     <Link href="#" onClick={() => void alert("hi")} tabIndex={3} />,
+    /* eslint-enable react/jsx-key */
   ];
 
   it("renders a styled external link", () => {

src/webutil/browserLocalStore.js

@@ -49,12 +49,7 @@ export default class BrowserLocalStore implements LocalStore {
     }
     const stringified = JSON.stringify(data);
 
-    try {
-      window.localStorage[this.cacheKey(key)] = stringified;
-    } catch (e) {
-      // Probably went over the storage limit... that's not good.
-      throw e;
-    }
+    window.localStorage[this.cacheKey(key)] = stringified;
   }
 
   /*

src/webutil/checkedLocalStore.js

@@ -43,7 +43,7 @@ export default class CheckedLocalStore implements LocalStore {
       if (deepEqual(data, JSON.parse(JSON.stringify(data)))) {
         return;
       }
-    } catch (_) {}
+    } catch (_) {} // eslint-disable-line no-empty
     throw new Error(`bad value: ${data}`);
   }
 }