Prompt char not displayed correctly in first sub-shell

[rodrigobdz]

• I am on the latest Hyper.app version
• I have searched the issues of this repo and believe that this is not a duplicate

• OS version and name: macOS 10.13.6
• Hyper.app version: 2.1.2
• Link of a Gist with the contents of your .hyper.js:
  Default config aside from font size. https://gist.github.com/rodrigobdz/122dbf2925e0c3691dffa3ee8191ce4e
• Relevant information from devtools: N/A
• The issue is reproducible in vanilla Hyper.app: Yes

Issue

Prompt char ❯ is not being displayed correctly when I open a fish shell for the first time. I'm using the mooji prompt which includes the char. I have also tried using fish -l without success.