Reenable no-non-null

.eslintrc

@@ -5,15 +5,12 @@
 		"plugin:@typescript-eslint/recommended"
 	],
 	"parser": "@typescript-eslint/parser",
-	"parserOptions": {
-		// trade off between having a warning without consequences on main
-		// and having no warning but non-descriptive errors when using typescript@^3.8 syntax
-		"warnOnUnsupportedTypeScriptVersion": false
-	},
 	"plugins": ["@typescript-eslint"],
 	"rules": {
 		// required for window.Element
 		"@typescript-eslint/ban-ts-ignore": "off",
+		// It's easily missed so we enforce and explicit eslint-disable-next-line to highlight the non-null assertion.
+		"@typescript-eslint/no-non-null-assertion": "error",
 		// I find this rule not very helpful since it prevents me from ordering
 		// functions in a file by importance e.g. default export at the top
 		"@typescript-eslint/no-use-before-define": "off",