This is a rather bizarre bug that started happening once I updated to 3.0.0.
I have a keyboard with the Portuguese layout: https://en.wikipedia.org/wiki/Portuguese_keyboard_layout#/media/File:KB_Portuguese.svg
Every time I try to type ~, ^ or 麓 or ` Hyper seems to write "Dead" instead
Usually these characters are normally paired with another letter (like 茫) only appearing after being followed by one. But regardless of being followed or not Hyper will always add "Dead".
I have a similar issue that might be related to this. I am not sure if I should log a separate issue for it. In my case when I hit the AltGr button on my keyboard hyper returns AltGraph as text in the terminal. My keyboard layout is Icelandic and this happens with no plugins enabled.
Ubuntu 18.04
And I am running the same version 3.0.0 Canary 3
This happened after the upgrade from 2.1.0 that I had before.
I just tested 3.0.0-canary.2 and this is an issue there, however using 3.0.0-canary.1 is fine and I don't see this happening there so this is something that gets introduced in 3.0.0-canary.2 for me at least.
I can confirm that canary.1 does indeed work so the bugs are likely related
Pretty sure your terminal is possessed.
I have the same issue as @garyx on my machine (Ubuntu 18.04 / German keyboard)

Having the exact same issue, but with stable. Also it could not identify my Home or End keys without having
keymaps: {
"editor:moveBeginningLine": "Home",
"editor:moveEndLine": "End"
}
in the configuration.
This should be fixed on 3.0.0-canary.5. Please reopen if it pops up again.
Most helpful comment
Pretty sure your terminal is possessed.