(types): enforce stricter typings (#475)

- noUnusedParameters, noImplicitReturns, and noFallthroughCasesInSwitch
  - improve typings for 1 unused parameter and 1 implicit return

- also remove noImplicitAny as that's redundant with strict: true

src/babelPluginTsdx.ts

@@ -47,7 +47,7 @@ export const createConfigItems = (type: any, items: any[]) => {
   });
 };
 
-export const babelPluginTsdx = babelPlugin.custom((babelCore: any) => ({
+export const babelPluginTsdx = babelPlugin.custom(() => ({
   // Passed the plugin options.
   options({ custom: customOptions, ...pluginOptions }: any) {
     return {

src/createEslintConfig.ts

@@ -14,7 +14,7 @@ export async function createEslintConfig({
   pkg,
   rootDir,
   writeFile,
-}: CreateEslintConfigArgs): Promise<CLIEngine.Options['baseConfig']> {
+}: CreateEslintConfigArgs): Promise<CLIEngine.Options['baseConfig'] | void> {
   const isReactLibrary = Boolean(getReactVersion(pkg));
 
   const config = {

tsconfig.json

@@ -11,8 +11,10 @@
     "module": "commonjs",
     "rootDir": "src",
     "strict": true,
-    "noImplicitAny": true,
     "noUnusedLocals": true,
+    "noUnusedParameters": true,
+    "noImplicitReturns": true,
+    "noFallthroughCasesInSwitch": true,
     "skipLibCheck": true,
     "target": "es2017"
   }