title: Firebase initWitURL crashes [FRepo initTransactions]: unrecognized selector
body: <p>I have set up two similar firebase applications.
  In both cases I call</p>
  
  <pre><code>self.firebase  = [[Firebase alloc] initWithUrl:kFirebaseRoot];
  </code></pre>
  
  <p>in one case everything works fine.
  In the other case I get a crash</p>
  
  <p><strong>2014-05-19 11:18:59.726 MyApp[28041:60b] * Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[FRepo initTransactions]: unrecognized selector sent to instance 0x8f50c10'
  <em></strong> First throw call stack:*</em></p>
  
  <pre><code>0   CoreFoundation                      0x023131e4 __exceptionPreprocess + 180
  
  1   libobjc.A.dylib                     0x020928e5 objc_exception_throw + 44
  2   CoreFoundation                      0x023b0243 -[NSObject(NSObject) doesNotRecognizeSelector:] + 275
  3   CoreFoundation                      0x0230350b ___forwarding___ + 1019
  4   CoreFoundation                      0x023030ee _CF_forwarding_prep_0 + 14
  5   MyApp                              0x0002b63b -[FRepo initWithRepoInfo:] + 187
  6   MyApp                              0x0002ab05 -[FRepoManager getLocalRepo:] + 597
  7   MyApp                              0x0002b3ff +[FRepoManager getRepo:] + 111
  8   MyApp                              0x000544dc -[Firebase initWithUrl:] + 204
  9   MyApp                              0x000172f2 -[FLPresenceManager initFirebase] + 194
  </code></pre>
  
  <p>This appears to be something going on within <code>Firebase</code>, so I presume there must be something different in the way I have set up the app in the two cases. However, I cannot see a difference.
  Can anyone offer any clues?</p>