Looking at the error, it seems to be a syntax error on the header template after the changes you performed.
Im sharing an out of the box header template so you can fix it.
{% assign homeurl = website.adx_partialurl %}
<div class="navbar navbar-inverse navbar-static-top" role="navigation">
 <div class="container">
 <div class="navbar-header">
 <div class="visible-xs-block">
 {% editable snippets 'Mobile Header' type: 'html' %}
 </div>
 <div class="visible-sm-block visible-md-block visible-lg-block navbar-brand">
 {% editable snippets 'Navbar Left' type: 'html' %}
 </div>
 <button type="button" class="navbar-toggle collapsed" title="{{ snippets["Header/Toggle Navigation"] | default: resx['Toggle_Navigation'] | h }}" data-toggle="collapse" data-target="#navbar" aria-expanded="false" onclick="setHeight();">
 <span class="sr-only">{{ snippets["Header/Toggle Navigation"] | default: resx['Toggle_Navigation'] | h }}</span>
 <span class="icon-bar"></span>
 <span class="icon-bar"></span>
 <span class="icon-bar"></span>
 </button>
 </div>
 <div id="navbar" class="navbar-collapse collapse">
 {% assign primary_nav = weblinks["Primary Navigation"] %}
 {% if primary_nav %}
 <div class="navbar-right menu-bar {% if primary_nav.editable %}xrm-entity xrm-editable-adx_weblinkset{% endif %}" data-weblinks-maxdepth="2">
 <ul class="nav navbar-nav weblinks" role="menubar">
 {% for link in primary_nav.weblinks %}
 {% unless forloop.first %}
 <li class="divider-vertical" aria-hidden="true"></li>
 {% endunless %}
 {% if link.display_page_child_links %}
 {% if link.url != null %}
 {% assign sublinks = sitemap[link.url].children %}
 {% endif %}
 {% else %}
 {% assign sublinks = link.weblinks %}
 {% endif %}
 <li role="none" class="weblink {% if sublinks.size > 0 %} dropdown{% endif %}">
 <a role="menuitem"
 aria-label="{{ link.name | escape }}"
 {% if sublinks.size > 0 -%}
 href="#" class="dropdown-toggle" data-toggle="dropdown"
 {%- else -%}
 href="{{ link.url | escape }}"
 {%- endif -%}
 {%- if link.Open_In_New_Window %} target="_blank" {% endif -%}
 {%- if link.nofollow %} rel="nofollow"{% endif -%}
 {%- if link.tooltip %} title="{{ link.tooltip | escape }}"{% endif %}>
 {%- if link.image -%}
 {%- if link.image.url startswith '.' -%}
 <span class="{{ link.image.url | split:'.' | join }}" aria-hidden="true"></span>
 {%- else -%}
 <img src="{{ link.image.url | escape }}"
 alt="{{ link.image.alternate_text | default:link.tooltip | escape }}"
 {% if link.image.width %}width="{{ link.image.width | escape }}" {% endif %}
 {% if link.image.height %}height="{{ link.image.height | escape }}" {% endif %} />
 {%- endif -%}
 {%- endif -%}
 {%- unless link.display_image_only -%}
 {{ link.name | escape }}
 {%- endunless -%}
 {%- if sublinks.size > 0 -%}
 <span class="caret"></span>
 {%- endif -%}
 </a>
 {% if sublinks.size > 0 %}
 <ul class="dropdown-menu" role="menu">
 {% if link.url %}
 <li role="none">
 <a role="menuitem"
 aria-label="{{ link.name | escape }}"
 href="{{ link.url }}"
 {% if link.Open_In_New_Window %} target="_blank" {% endif %}
 {% if link.nofollow %}rel="nofollow" {% endif %}
 {% if link.tooltip %}title="{{ link.tooltip | escape }}" {% endif %}>{{ link.name | escape }}</a>
 </li>
 <li class="divider"></li>
 {% endif %}
 {% for sublink in sublinks %}
 <li role="none">
 <a role="menuitem"
 aria-label="{{ sublink.name | default:sublink.title | escape }}"
 href="{{ sublink.url }}"
 {% if sublink.Open_In_New_Window %} target="_blank" {% endif %}
 {% if sublink.nofollow %}rel="nofollow" {% endif %}
 {% if sublink.tooltip %}title="{{ sublink.tooltip | escape }}" {% endif %}>
 {{ sublink.name | default:sublink.title | escape }}
 </a>
 </li>
 {% endfor %}
 </ul>
 {% endif %}
 </li>
 {% endfor %}
 {% assign search_enabled = settings['Search/Enabled'] | boolean | default:true %}
 {% if search_enabled %}
 <li class="divider-vertical" aria-hidden="true"></li>
 <li class="dropdown" role="none">
 <a id="search" class="navbar-icon" href="#" data-toggle="dropdown"
 role="button" aria-haspopup="true" aria-expanded="false"
 aria-label="{{ snippets["Header/Search/ToolTip"] | default:resx["Search_DefaultText"] | escape }}" >
 <span class="glyphicon glyphicon-search"></a>
 </a>
 <ul class="dropdown-menu dropdown-search">
 <li>
 {% include 'Search' %}
 </li>
 </ul>
 </li>
 {% endif %}
 <li class="divider-vertical" aria-hidden="true"></li>
 {% if website.languages.size > 1 %}
 <li class="dropdown" role="none">
 <a class="dropdown-toggle" href="#" data-toggle="dropdown" role="menuitem" aria-label="{{ website.selected_language.name | escape }}" aria-haspopup="true" aria-expanded="false" title="{{ website.selected_language.name | escape }}">
 <span class="drop_language">{{ website.selected_language.name | escape }}</span>
 <span class="caret"></span>
 </a>
 {% include 'Languages Dropdown' %}
 </li>
 <li class="divider-vertical" aria-hidden="true"></li>
 {% endif %}
 {% if user %}
 <li class="dropdown" role="none">
 <a href="#" class="dropdown-toggle" title="{{ user.fullname | escape }}" data-toggle="dropdown" role="menuitem" aria-haspopup="true" aria-expanded="false">
 <span class="username">{{ user.fullname | escape }}</span>
 <span class="caret"></span>
 </a>
 <ul class="dropdown-menu" role="menu">
 {% assign show_profile_nav = settings["Header/ShowAllProfileNavigationLinks"] | boolean | default:true %}
 {% if show_profile_nav %}
 {% assign profile_nav = weblinks["Profile Navigation"] %}
 {% if profile_nav %}
 {% for link in profile_nav.weblinks %}
 <li role="none">
 <a role="menuitem" aria-label="{{ link.name | escape }}" href="{{ link.url | escape }}" title="{{ link.name | escape }}">{{ link.name | escape }}</a>
 </li>
 {% endfor %}
 {% endif %}
 {% else %}
 <li role="none"><a role="menuitem" aria-label="{{ snippets["Profile Link Text"] | default:resx["Profile_Text"] | escape }}" href="{{ sitemarkers['Profile'].url | escape }}">{{ snippets["Profile Link Text"] | default:resx["Profile_Text"] | escape }}</a></li>
 {% endif %}
 <li class="divider" role="separator" aria-hidden="true"></li>
 <li role="none">
 <a role="menuitem" aria-label="{{ snippets["links/logout"] | default:resx["Sign_Out"] | escape }}" href="{% if homeurl%}/{{ homeurl }}{% endif %}{{ website.sign_out_url_substitution }}" title="{{ snippets["links/logout"] | default:resx["Sign_Out"] | escape }}">
 {{ snippets["links/logout"] | default:resx["Sign_Out"] | escape }}
 </a>
 </li>
 </ul>
 </li>
 {% else %}
 <li role="none">
 <a role="menuitem" aria-label="{{ snippets["links/login"] | default:resx["Sign_In"] | escape }}" href="{% if homeurl%}/{{ homeurl }}{% endif %}{{ website.sign_in_url_substitution }}" title="{{ snippets["links/login"] | default:resx["Sign_In"] | escape }}">
 {{ snippets["links/login"] | default:resx["Sign_In"] | escape }}
 </a>
 </li>
 {% endif %}
 </ul>
 {% editable primary_nav %}
 </div>
 {% endif %}
 <div class="navbar-right hidden-xs">
 {% editable snippets 'Navbar Right' type: 'html' %}
 </div>
 </div>
 </div>
</div>
{% substitution %}
 {% assign current_page = page.id %}
 {% assign sr_page = sitemarkers["Search"].id %}
 {% assign forum_page = sitemarkers["Forums"].id %}
 {% if current_page == sr_page or current_page == forum_page %}
 {% assign section_class = "section-landing-search" %}
 {% if current_page == forum_page %}
 {% assign section_class = "section-landing-forums" %}
 {% endif %}
 <section class="page_section {{ section_class | h }} color-inverse">
 <div class="container">
 <div class="row ">
 <div class="col-md-12 text-center">
 {% if current_page == sr_page %}
 <h1 class="section-landing-heading">{% editable snippets 'Search/Title' default: resx["Discover_Contoso"] %}</h1>
 {% include 'Search' %}
 {% endif %}
 </div>
 </div>
 </div>
 </section>
 {% endif %}
{% endsubstitution %}
<script type="text/javascript">
 window.onload = function() {
 if(window.navigator.appName == "Microsoft Internet Explorer" || window.navigator.userAgent.indexOf("Trident") > 0){
 var searchElement = document.getElementById("search");
 if (searchElement != null) searchElement.setAttribute("href", "");
 }
 };
 function setHeight(){
 var windowHeight = window.innerHeight - 140;
 var navbar = document.getElementById("navbar");
 if (navbar) {
 navbar.style.maxHeight = windowHeight + "px";
 }
 }
 window.addEventListener('resize', function (event) {
 setHeight();
 });
</script>