``` const diff = require('microdiff').default const a1 = {"a": { "b": 1 }} const a2 = {"a": null} console.log(diff(a1, a2)) ``` ``` /Users/.../node_modules/microdiff/dist/index.cjs:8 if (!(key in newObj)) { ^ TypeError: Cannot use 'in' operator to search for 'b' in null ```