Spaces and inline R YAML strings

[ekstroem]

I'm trying to add a twitter icon to the subtitle YAML parameter. Here's a reproducible piece of working code which produces the output I'm after.

---
title: "Presentation Ninja"
subtitle: ' `r fontawesome::fa("twitter", fill = "steelblue")` @ClausEkstrom'
author: "Claus Ekstrøm"
date: "Some day"
output:
  xaringan::moon_reader:
    lib_dir: libs
    css: ['default']
    seal: true
    nature:
      ratio: '16:9'
      slideNumberFormat: '%current%' 
      highlightStyle: ir-black
      highlightLines: true
      countIncrementalSlides: false
      beforeInit: "js/zoom.js"
---

Ohoy sailor

Notice the space between the backtick and the quote on the subtitle line. If I remove that (which I did initially), such that it beomes

subtitle: '`r fontawesome::fa("twitter", fill = "steelblue")` @ClausEkstrom'

then I get no twitter icon. I have no idea why I should get different results from these two formats.

If I look at the resulting html-code then I can see why the output is different, since the working code (first example above) produces one long line

## <svg style="height:0.8em;top:.04em;position:relative;fill:steelblue;" viewBox="0 0 512 512"><path d="M459.37 151.716c.325 ... 39.308-52.628 54.253z"/></svg> <span class="citation">@ClausEkstrom</span>

while the code without the space produces 4 lines including a <p> ... </p>:

## <svg style="height:0.8em;top:.04em;position:relative;fill:steelblue;" viewBox="0 0 512 512">
<path d="M459.37 151.716c.325 ... 39.308-52.628 54.253z"/>
</svg>
<p><span class="citation">@ClausEkstrom</span></p>

Why is that and shouldn't they give the same?