Burn input not registering values

[EstherSeyi]

Describe the bug
Unable to burn minted squeeth.

To Reproduce
Steps to reproduce the behavior:

1. Mint squeeth
2. Go to the vault page and try to burn minted squeeth in the "adjust debt" form

Expected behavior

1. On the vault page, a user should be able to type minus followed by the amount of squeeth(e.g "-12") to burn and choose a collateral ratio.
2. Burn button should become enabled and red if the input is valid.
3. Specified squeeth amount should be burnt after the burn button is clicked.

Screenshots
If applicable, add screenshots to help explain your problem.

burn.mp4

Additional context
Cc: @alexisgauba