Does an expression with undefined behaviour that is never actually executed make a program erroneous?

Question

In many discussions about undefined behavior (UB), the point of view has been put forward that in the mere presence in a program of any construct that has UB in a p

Answer 1

No. Example:

struct T {
    void f() { }
};
int main() {
    T *t = nullptr;
    if (t) {
        t->f(); // UB if t == nullptr but since the code tested against that
    }
}