Calling relationship with non existing foreign key returns null instead of throwing error

[mesiarm]

• Laravel Version: #.#.#
• 8.27.0
• PHP Version: #.#.#
• 7.4.3
• Database Driver & Version:
• Postgres 13

Description:

Calling relationship with non existing foreign key returns null instead of throwing error.

Steps To Reproduce:

1. Create relationship in model (for example $user->role)
2. Fill custom non-existing foreign key (for example: (return $this->belongsTo(Role::class, 'x');)
3. Create $user = new User(); object and set role_id property to existing role id.
4. Calling relationship $user->role returns null (looks like role doesnt exist in database) instead of throwing error.

[taylorotwell]

Feel free to PR a change in behavior you want to make - sounds like this would be a breaking change though.