[Vuejs]-Why is this error coming Uncaught (in promise) TypeError: Cannot read property 'created' of undefined in vue.js

1. I found the problem with my code at line 42

then(this.router.push("/")).catch(err => console.log(err))

2. The right way to call router is by $ the code would be replaced by

then(() => this.$router.push("/")).catch(err => console.log(err))