InsertQuery.execute quietly assumes synchronous cursor
Have you tested with 3.0a? I just added a test-case to 3.0a which would indicate that this case is being handled properly:

```diff
diff --git a/tests/sqliteq.py b/tests/sqliteq.py
index ebda3b7..cd7aecb 100644
--- a/tests/sqliteq.py
+++ b/tests/sqliteq.py
@@ -69,6 +69,11 @@ class BaseTestQueueDatabase(object):
         self.assertRaises(OperationalError, curs.fetchone)
         self.database.stop()
 
+    def test_integrity_error(self):
+        self.database.start()
+        u = User.create(name='u')
+        self.assertRaises(IntegrityError, User.create, name='u')
+
     def test_query_execution(self):
         qr = User.select().execute()
         self.assertEqual(self.database.queue_size(), 0)
``` No this is from 2.10.2, when 3.0 will be released? I tested this locally with Sqlite 2.10 and received the integrity error as expected:

```python
In [1]: from playhouse.sqliteq import *

In [2]: from peewee import *

In [3]: db = SqliteQueueDatabase('/tmp/testing.db')

In [4]: class Sample(Model):
   ...:     name = TextField(unique=True)
   ...:     class Meta:
   ...:         database = db
   ...:         

In [5]: db.start()
Out[5]: False

In [6]: Sample.create_table()

In [7]: u = Sample.create(name='s1')

In [8]: Sample.create(name='s1')
IntegrityError                            Traceback (most recent call last)
<ipython-input-8-1af0ec3b11a0> in <module>()
----> 1 Sample.create(name='s1')
....
     60             raise ResultTimeout('results not ready, timed out.')
     61         if self._exc is not None:
---> 62             raise self._exc
     63         self._ready = True
     64 

IntegrityError: UNIQUE constraint failed: sample.name
``` Yes i forgot to mention small thing, please add primary_key=True to Sample, and you see that it occur.
When executing insert query, execute method assumes that synchronous code is executed.

If async cursor was used insted, method will silently return passed row, even though exception should be thrown.

Simple test, using SqliteQueueDatabase test this:

```
        model.Payment.create(primarykey="xyz", value=5)
        with self.assertRaises(IntegrityError):
           model.Payment.create(primarykey="xyz", value=5)
```

This should throw ```IntegrityError: UNIQUE constraint failed``` but silently passed payment is returned.