Unable to locate sign

Put the summary of the bug you're having here

*What I expected to happen was...: Nonthing.

*What actually happened was...: I was walking around in an adventure map and suddenly I get the message saying "Unable to locate sign at (Where's the sign here)

Steps to Reproduce:
1. Download any map with a lot of signs in it (The signs must have text on them!)
2. Walk around for a bit.
3. See spam allover your chat.