How to prevent key input while player is typing in chat?

So, I wrote a gun script, but when the player types the letters E or R in the chat, it will toggle the safety or reload the gun, accordingly.

I don't want this to happen. I've seen plenty of games that don't do this, so I know there's a way.

Here's the script. I've shortened it down considerably, to the parts that are relevant to this problem.

function onKeyPress(inputObject, gameProcessedEvent)
    if inputObject.KeyCode == Enum.KeyCode.R then
        print("Key R pressed!")
    elseif inputObject.KeyCode == Enum.KeyCode.E then
        print("Key E pressed!")
    end
end

tool.Equipped:connect(function(mouse)
    game:GetService("UserInputService").InputBegan:connect(onKeyPress)
end)