Error in AirtestIDE20 \ poco \ sdk \ Selector.py

**Describe the bug**
Exceptions are being processed at the time of another exception.
```
`[Start running..]
save log in 'C:/AirtestIDE20/AirtestLog\4291660d4891d5bc2ea0574442029ffa'
[rpc]connected
[rpc]connected
======================================================================
ERROR: runTest (app.widgets.code_runner.ide_launcher.AirtestIDECase)
----------------------------------------------------------------------
Traceback (most recent call last):
File "C:\AirtestIDE20\poco\sdk\Selector.py", line 137, in selectImpl
result = [self.selectImpl(cond, multiple, root, maxDepth, onlyVisibleNode, includeRoot)[i]]
IndexError: list index out of range

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
File "airtest\cli\runner.py", line 65, in runTest
File "site-packages\six.py", line 693, in reraise
File "airtest\cli\runner.py", line 61, in runTest
File "C:\Users\wazzapps_user\Desktop\untitled.air\untitled.py", line 23, in
merge(dnk)
File "C:\Users\wazzapps_user\Desktop\untitled.air\untitled.py", line 18, in merge
cat[i].focus('center').drag_to(cat[len(cat)-i-1], duration=0.2)
File "C:\AirtestIDE20\poco\proxy.py", line 246, in __getitem__
pos = uiobj.get_position()
File "C:\AirtestIDE20\poco\proxy.py", line 72, in wrapped
return func(proxy, *args, **kwargs)
File "C:\AirtestIDE20\poco\proxy.py", line 613, in get_position
pos = self.attr('pos')
File "C:\AirtestIDE20\poco\proxy.py", line 39, in wrapped
return func(self, *args, **kwargs)
File "C:\AirtestIDE20\poco\proxy.py", line 734, in attr
nodes = self._do_query(multiple=False)
File "C:\AirtestIDE20\poco\proxy.py", line 872, in _do_query
self._nodes = self.poco.agent.hierarchy.select(self.query, multiple)
File "C:\AirtestIDE20\poco\freezeui\hierarchy.py", line 90, in select
return self.selector.select(query, multiple)
File "C:\AirtestIDE20\poco\sdk\Selector.py", line 78, in select
return self.selectImpl(cond, multiple, self.getRoot(), 9999, True, True)
File "C:\AirtestIDE20\poco\sdk\Selector.py", line 140, in selectImpl
u'Query results index out of range. Index={} condition "{}" from root "{}".'.format(i, cond, root))
poco.sdk.exceptions.NoSuchTargetException: Query results index out of range. Index=1 condition "('and', (('attr=', ('texture', '0')),))" from root "".

----------------------------------------------------------------------
Ran 1 test in 1.319s

FAILED (errors=1)
[Finished]`
```

**To Reproduce**
I use this script:
```
`from poco.drivers.unity3d import UnityPoco
poco = UnityPoco()

dnk=poco(texture="0")
def merge(cat):
from poco.drivers.unity3d import UnityPoco
poco = UnityPoco()
if len(cat) > 1:
for i in range(0, len(cat)):
cat[i].focus('center').drag_to(cat[len(cat)-i-1], duration=0.2)
from poco.drivers.unity3d import UnityPoco
poco = UnityPoco()

merge(dnk)`
```

** Expected behavior **
Characters in the game must move to other similar characters.

** python version: ** `python3.6`

** poco version: ** `1.0.76`

** Smartphone (please complete the following information): **
On all the devices that I managed to use.
About 5 pieces