Possible fix: "Error: Call to a member function getLoadQueryAutojoin() on a non-object"

I recently set up ProcessWire on some cloud hosting (from Vidahost), and encountered the same error as [mentioned on the forum](http://processwire.com/talk/topic/2228-trouble-with-install-rackspace-cloudsites/).

I eventually managed to trace the problem back - please bear with me :)

  - The "non-object" mentioned in the error was the "type" property (which was NULL) of the fieldtypes list for a template (the loop in Pages.php).
  - It was NULL because fieldtype information was not set when initialised.
  - ... because the list of modules could not be loaded and returned to the functions relying on them.

I think this was caused by the `findModuleFiles()` function. Although it seemed it could create the file on the first call of this function, the combination of network file system in the cloud hosting (which introduced a delay in file access) and the LOCK_EX parameter meant that the data couldn't actually be written to it.

On next calls to the `findModuleFiles()` function, the cache file "exists", but its empty contents are returned - resulting in the error.

From testing, my proposed change removes the LOCK_EX parameter, which allows the data to be written to the file correctly. In addition, if the cache exists - the content is only returned if the array isn't empty.