PAINTROID-806: SourceFile - org.catrobat.paintroid.MainActivity.onCreate

[icarusiftctts]

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Fixed fragment restoration crash in MainActivity (NoSuchMethodException) by adding safe fragment retrieval and replacing unsafe cast. Should avoid duplicate fragment creation. This is highlighted as Problem 1.

SourceFile - org.catrobat.paintroid.MainActivity.onCreate - https://catrobat.atlassian.net/browse/PAINTROID-806

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[icarusiftctts]

Handled corrupted temporary autosave file (KryoBufferUnderflowException)

The autosave file can become truncated, which causes Kryo to throw BufferUnderflowException.

fix catches the exception and deletes the corrupted file, starting a new canvas.

This should fix Problem 2.