title: Gulp-twig console says "Error parsing twig template" despite rendered output being fine
body: <p>I have a page twig which consumes a component file which in turn consumes another file. I need to set all content for any of these files in the page file.</p>
  
  <p>In my page twig file:</p>
  
  <pre><code>{% set content = {
    title: 'page title',
    accordion: {
      'text': 'TitleA'
    }
  }
  %}
  
  {% include "component.twig" with content %}
  </code></pre>
  
  <p>In component.twig:</p>
  
  <pre><code>{% set settings = {
      'class': 'my-class',
      'style': 'primary'
    }|merge(accordion)
  %}
  
  {% include "button.twig" with settings %}
  </code></pre>
  
  <p>In button.twig:</p>
  
  <pre><code>&lt;button class="{{ class }} button--{{ style }}" type="button"&gt;{{ text }}&lt;/button&gt;
  </code></pre>
  
  <p>Im using gulp-twig. The above works however i get this error in my console. </p>
  
  <p><a href="https://github.com/zimmen/gulp-twig" rel="nofollow">https://github.com/zimmen/gulp-twig</a></p>
  
  <pre><code>Error parsing twig template /Users/me/myproject/src/components/component.twig:
  TypeError: Cannot read property '_keys' of undefined
      at /Users/me/myproject/node_modules/gulp-twig/node_modules/twig/twig.min.js:10:3579
      at Array.forEach (native)
      at Object.Twig.forEach (/Users/me/myproject/node_modules/gulp-twig/node_modules/twig/twig.min.js:8:822)
      at Twig.filters.merge (/Users/me/myproject/node_modules/gulp-twig/node_modules/twig/twig.min.js:10:3399)
      at Twig.filter (/Users/me/myproject/node_modules/gulp-twig/node_modules/twig/twig.min.js:10:10126)
      at Twig.expression.definitions.parse (/Users/me/myproject/node_modules/gulp-twig/node_modules/twig/twig.min.js:9:21538)
      at /Users/me/myproject/node_modules/gulp-twig/node_modules/twig/twig.min.js:9:28849
      at Array.forEach (native)
      at Object.Twig.forEach (/Users/me/myproject/node_modules/gulp-twig/node_modules/twig/twig.min.js:8:822)
      at Twig.expression.parse (/Users/me/myproject/node_modules/gulp-twig/node_modules/twig/twig.min.js:9:28724)
  Error parsing twig template /Users/me/myproject/src/components/component.twig:
  TypeError: Cannot read property '_keys' of undefined
      at /Users/me/myproject/node_modules/gulp-twig/node_modules/twig/twig.min.js:10:3579
      at Array.forEach (native)
      at Object.Twig.forEach (/Users/me/myproject/node_modules/gulp-twig/node_modules/twig/twig.min.js:8:822)
      at Twig.filters.merge (/Users/me/myproject/node_modules/gulp-twig/node_modules/twig/twig.min.js:10:3399)
      at Twig.filter (/Users/me/myproject/node_modules/gulp-twig/node_modules/twig/twig.min.js:10:10126)
      at Twig.expression.definitions.parse (/Users/me/myproject/node_modules/gulp-twig/node_modules/twig/twig.min.js:9:21538)
      at /Users/me/myproject/node_modules/gulp-twig/node_modules/twig/twig.min.js:9:28849
      at Array.forEach (native)
      at Object.Twig.forEach (/Users/me/myproject/node_modules/gulp-twig/node_modules/twig/twig.min.js:8:822)
      at Twig.expression.parse (/Users/me/myproject/node_modules/gulp-twig/node_modules/twig/twig.min.js:9:28724)
  </code></pre>
  
  <p>I can make the error going away by creating the following object. The weird thing however is that from looking at the page I can see TitleA is used not TitleB. </p>
  
  <pre><code>{% set accordion = {
    'text': 'TitleB'
  }
  %}
  </code></pre>
  
  <p>Ive tried different syntax eg:</p>
  
  <pre><code>{% include "button.twig" with accordion|merge({class: "my-class", style: "primary"}) %}
  </code></pre>