TypeError: Assignment to constant variable

このエラーの原因

You declared a variable with const and later tried to reassign it. Const variables cannot be reassigned after initialization. Note that for objects/arrays, the reference is constant but the contents can still be mutated.

修正方法

Use let instead of const if you need to reassign the variable. If you need a mutable reference, use let. If you need to modify an object's properties, you can still do so with const; only reassignment is prohibited.

const x = 1; x = 2; // TypeError: Assignment to constant variable