Eager Load Relation, When Relation Doesn't Exist

So, I have a Product model which belongsTo('App\Tax'). A Product may or may not be associated with a Tax (the tax_id fk in Product could be null).

The query below works fine as long as I have at least one Product associated with a Tax:

\App\Product::with("tax")->get()

It starts throwing the following exception, when none of the Product's have associated Taxes:

Illuminate\Database\QueryException with message 'SQLSTATE[22P02]: Invalid text 
representation: 7 ERROR:  invalid input syntax for uuid: "0" (SQL: select * 
from "taxes" where "taxes"."id" in (0))'

While this exception is quite understandable, my question is how do I avoid this situation?

Note: The tax.id column is of postgres uuid type.

via Chebli Mohamed