zulip/static/templates/blueslip_stacktrace.hbs

<div class="stacktrace-header">
    <div class="warning-symbol">
        <i class="fa fa-exclamation-triangle"></i>
    </div>
    <div class="message"><strong>Error:</strong> {{ error }}</div>
    <div class="exit"></div>
</div>
<div class="stacktrace-content">
    {{#each stackframes}}
        <div data-full-path="{{ full_path }}" data-line-no="{{ line_number }}">
            <div class="stackframe">
                <i class="fa fa-caret-right expand"></i>
                <span class="subtle">at</span>
                {{#if function_name}}
                {{ function_name.scope }}<b>{{ function_name.name }}</b>
                {{/if}}
                <span class="subtle">{{ show_path }}:{{ line_number }}</span>
            </div>
            <div class="code-context" style="display: none">
                <div class="code-context-content">
                    {{~#each context~}}
                        <div {{#if focus}}class="focus-line"{{/if}}><span class="line-number">{{ line_number }}</span> {{ line }}</div>
                    {{~/each~}}
                </div>
            </div>
        </div>
    {{/each}}
</div>