Never seen this error maybe nostr:npub1ye5ptcxfyyxl5vjvdjar2ua3f0hynkjzpx552mu5snj3qmx5pzjscpknpr knows something. What browser are you using?
Discussion
This is due to the window.crypto api not being available on http connections... For some "security" reasons https://developer.mozilla.org/en-US/docs/Web/API/Web_Crypto_API
noStrudel uses it to encrypt the nsec when its storing it locally and I have not had a chance to update it to NIP-49 yet