Http.Error not caught for invalid protocol in Firefox

[absynce]

I was trying to verify my error branch is working PageLoaded (Err _) so I intentionally used an invalid protocol: "htp".

✔️ In Chrome it's caught in the error branch as expected.
❌ In Firefox it throws a JavaScript error: "A network error occurred."

Here's my SSCCE: https://ellie-app.com/brMS86CJwa1/2.

Firefox 56.0 (64-bit)
Ubuntu 17.04
Elm 0.18

Checklist

• ✅ Does your title concisely summarize the problem?
  I hope so. I'm fairly new to Elm so my terminology might be a bit off.
• ✅ Did you include a minimal, reproducible example? Is it an SSCCE?
  Yes, https://ellie-app.com/brMS86CJwa1/2.
• ✅ What OS and browser are you using? What versions?
  Ubuntu 17.04 and Firefox 56.0 (64-bit)
• ✅ What version of Elm are you using?
  0.18

[process-bot]

Thanks for the issue! Make sure it satisfies this checklist. My human colleagues will appreciate it!

Here is what to expect next, and if anyone wants to comment, keep these things in mind.