When I write on a sign crashed Minecraft

Device: Sony Xperia U

Put the summary of the bug you're having here
Minecraft crashing

What I expected to happen was...:
Describe what you thought should happen here
Need Help

What actually happened was...:
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Need Help
Steps to Reproduce:

Put a step by step guide on how to trigger the bug here
1. Put a sign on everything
2.Write on sign
3. Minecraft Crashed