When a function within a block scope tries to access a variable declared with `const`/`let` on the wrapping scope a RefferenceError is thrown. Reproducible example: ``` { const a = true; // also happens with "let" declarations. function main() { console.log(a); } main(); } ``` Accessing `a` on the 4th line throws an error: "ReferenceError: Can't find variable: a". The expected behavior would be for the "a" variable to be in the scope of the function "main".