use strict mode

Signed-off-by: 迷渡 <justjavac@gmail.com>

Author: justjavac

tsconfig.json

@@ -11,6 +11,8 @@
     "allowSyntheticDefaultImports": true,
     "lib": ["es6"],
     "strict": true,
+    "alwaysStrict": true,
+    "strictNullChecks": true,
     "baseUrl": "./src"
   },
   "include": ["./src/**/*.ts", "types/**/*.d.ts"]