Code:
The game crashed whilst mouseclicked event handler
Error: java.lang.RuntimeException: java.lang.NullPointerException: Cannot invoke "net.minecraft.network.chat.Component.getString()" because the return value of "net.minecraft.client.gui.components.Button.m_6035_()" is null

Pressing mouse button 4 (normally an alias for "back") will crash the game with above code when pressed while in terminal.

Please post your minecraft log