Why can't I use a table alias and its original name in the same query when two tables are joined?

Suppose there are two tables created:

CREATE TABLE emp
(
EMPNO int,
EMPNAME varchar(255),
JOB varchar(255),
DEPTNO int
);

CREATE TABLE dept
(
LOC varchar(255),
DEPTNO int
);

I want to know which department has no job. I am using a left join as follows:

select dept.* 
from dept  
left join emp 
 on (dept.deptno=emp.deptno) 
where emp.empno is null;

But if I use an alias for dept or emp, then I can only use an alias and cannot use the name of the source table. For instance:

select dept.* 
from dept as d 
left join emp 
 on (dept.deptno=emp.deptno) 
where emp.empno is null;

I get the error "there is no such table: dept" from sqlite.

If I run operations on the same table, I can use the alias and name of the source table in the same query.

Does anyone know why?