Oracle: Delete row in a table using triggers while deleting value in another table

So, I basically have those 3 tables:

tbl_albums —-> (id, name)

tbl_album_has_songs —-> (id_album, id_song)

tbl_songs —–> (id, name)

I need to write a trigger that deletes a row from table tbl_album when there are no more songs associated with that album on tbl_album_has_songs.

To do this, I need to count how many times a certain tbl_albums.id = tbl_album_has_songs.id_album appears on tbl_album_has_songs. If count is 0, then I delete the album from tbl_albums.

I've made the following trigger:

CREATE OR REPLACE TRIGGER delete_album after update or delete on tbl_album_has_songs
REFERENCING OLD AS old NEW AS new
FOR EACH ROW
declare lv NUMBER;
begin
select count(*) into lv from tbl_album_has_songs where id_album =:old.id_album;
if lv = 0 then 
delete from tbl_album where album.id = :old.id_album;
end if;
commit;
end;

but when I tried to delete some songs from tbl_album_has_songs it throws the following error:

Error starting at line 1 in command:
INSERT INTO tbl_equiporder VALUES (1,101,'11-sep-13',1000,1)
Error report:
SQL Error: ORA-04091: table S24585181.TBL_EQUIPORDER is mutating, trigger/function may not see it
ORA-06512: at "S24585181.TRIGGER_EQUIPORDER", line 9
ORA-04088: error during execution of trigger 'S24585181.TRIGGER_EQUIPORDER'
04091. 00000 -  "table %s.%s is mutating, trigger/function may not see it"
*Cause:    A trigger (or a user defined plsql function that is referenced in
           this statement) attempted to look at (or modify) a table that was
           in the middle of being modified by the statement which fired it.
*Action:   Rewrite the trigger (or function) so it does not read that table.

Any help?