add eslint and fix errors

Author: mbrinkl

.eslintignore

@@ -0,0 +1,2 @@
+build
+coverage

.eslintrc.json

@@ -0,0 +1,28 @@
+{
+  "root": true,
+  "settings": {
+    "react": {
+      "version": "detect"
+    }
+  },
+  "env": {
+    "browser": true,
+    "node": true
+  },
+  "parser": "@typescript-eslint/parser",
+  "parserOptions": {
+    "project": ["./tsconfig.json"]
+  },
+  "plugins": ["@typescript-eslint", "import", "react", "react-hooks"],
+  "extends": [
+    "eslint:recommended",
+    "plugin:@typescript-eslint/recommended",
+    "plugin:import/recommended",
+    "plugin:import/typescript",
+    "plugin:react/recommended",
+    "plugin:react-hooks/recommended"
+  ],
+  "rules": {
+    "react/react-in-jsx-scope": "off"
+  }
+}

.vscode/settings.json

@@ -0,0 +1,6 @@
+{
+  "editor.defaultFormatter": "esbenp.prettier-vscode",
+  "editor.formatOnSave": true,
+  "editor.tabSize": 2,
+  "editor.codeActionsOnSave": { "source.fixAll.eslint": true }
+}