When accessing non-existing properties it is expected behavior to throw an error.
This is the case in all other places.
It is also not reliably possible to determine whether a property exists beforehand.
it is not sufficient to call `property_exists()` as it may be available via `__get()`.
Instead of `property_exists()` or `isset()` it should call `$object->canGetProperty()` but this is not
guaranteed to be implemented and therefor doing such a check will not work in 2.0.x.
calling isset() may break code that works through __get() but has not implemented __isset() properly.
We may discuss this for 2.1 again but I am in favor of keeping it as is.
* 'master' of github.com:yiisoft/yii2: (79 commits)
Refactored app bootstrap logic.
Update authorization.md
Fixes#3052: Fixed the issue that cache dependency data is not reused when `reusable` is set true
start debug logging only if debug runs when bootstrap.
Update finnish translation
Add ODBC support to yii\db\Connection
updated error handler and requirement checker links.
fixed broken API links [skip ci]
added more doc [skip ci]
update class map.
Fixes#2034: Added `ContentNegotiator` to support response format and language negotiation
renamed attributes to attributeNames in model
updated phpdoc
Removed `Application::preload` in favor of `Application::bootstrap`
Update module-debug.md
Update model.md
Fixes
Update basics.md
typo fix [skip ci]
Added `HtmlResponseFormatter` and `JsonResponseFormatter`
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