PHP files without namespaces raise an exception

[Julien Janvier]

for example:

• an empty php file
• a procedural php script
• a class without namespace

In NamespaceExtractor.php line 35:
                                               
  No way to parse the namespace of this class  

we don't know which file, which class, etc...

such nodes are completely valid
they should be ignored and should not stop the program