symfony - Symfony2: catch fatal ClassNotFoundException -

in order improve cache generation in symfony2 project, want go through php classes (even vendor) , pre-generate annotation (because few actions, takes 5 sec on first access).

do achieve it, built cache warmer read php classes of projet, reflection class each 1 , call annotation_reader service on class / methods / properties.

this works fine classes, vendor might errors want catch: indeed cannot correct vendor... error vendor might throw classnotfoundexception fatal (eg. in doctrine/datafixtures/containerawareloader).

i want catch these errors (this not practices, executed once it's ok), usual catching don't work fatak. idea how it?