Code intelligence doesn't wrap non-highlighted code units

Currently, we expect that every code unit is wrapped into a span element. That's why the following logic has been implemented:

const el = [...line.childNodes].find(({ textContent }) => {
  if (charCount === d.start_char) return true;
    charCount += textContent.length;
    return false;
});

We receive start_char from the backend and get the Nth element using that number. However, the elements are not always wrapped into separate spans (like in this example):

<code>
  <span id="LC59" lang="go" data-testid="content" class="line code-navigation-line hll">
    <span class=""></span>
    <span class="hljs-keyword">if</span>
    <span class=""></span>
    <span class="cursor-pointer code-navigation js-code-navigation">c.cfg.Server.ClientAliveInterval</span>
    <span class=""></span>
    <span class="">&gt;</span>
    <span class=""></span>
    <span class="hljs-number">0</span>
    <span class=""></span>
    <span class="">{</span>
  </span>
</code>

However, the backend returns the following points for code units of c.cfg.Server.ClientAliveInterval:

• {"start_line"=>58, "start_char"=>4} for c
• {"start_line"=>58, "start_char"=>6} for cfg
• {"start_line"=>58, "start_char"=>10} for Server
• {"start_line"=>58, "start_char"=>17} for ClientAliveInterval

The problem should be fixed on the frontend, but backend may need to return either end_char or length to mark the end of a code unit.