hat does not throw. For example:</p>
<pre class="highlight swift"><code><span class="k">let</span> <span class="nv">possibleData</span><span class="p">:</span> <span class="kt">DataResponse</span><span class="o">&lt;</span><span class="kt">Data</span><span class="o">&gt;</span> <span class="o">=</span> <span class="o">...</span>
<span class="k">let</span> <span class="nv">withMyError</span> <span class="o">=</span> <span class="n">possibleData</span><span class="o">.</span><span class="n">mapError</span> <s