fix: in conditionals, don't render anything after an else branch

[joel-hamilton]

This PR enforces a simple rule: don't render anything after an else branch.

There are several bugs currently where if, unless and case conditionals can have branches that occur after an else render, or that branches after an else can actually cause the else branch itself not to render.

Fixes: #670 and #672

Example

<p>If</p>
{% if false %}
  don't show
  {%- else -%}
  show
  {%- else -%}
  don't show
{% endif %}

<p>If with Elsif</p>
{% if false %}
  don't show
  {%- else -%}
  show
  {%- elsif true -%}
  don't show
{% endif %}

<p>Unless</p>
{% unless true %}
  don't show
  {%- else -%}
  show
  {%- else -%}
  don't show
{% endunless %}

<p>Case</p>
{% case true %}
  {%- when false- %}
    don't show
  {%- else -%}
    show
  {%- else -%}
    don't show
{% endcase %}

<p>Case with When</p>
{% case true -%}
  {% when false -%}
    don't show (false)
  {%- else -%}
    show
  {%- else -%}
    don't show (second else)
  {%- when true -%}
    don't show (truthy when condition after else)
  {%- when true -%}
    don't show (truthy when condition after else)
{%- endcase %}

master Behaviour:

<p>If</p>
showdon't show

<p>If with Elsif</p>
don't show

<p>Unless</p>
showdon't show

<p>Case</p>
showdon't show

<p>Case with When</p>
don't show (truthy when condition after else)don't show (truthy when condition after else)

PR Behaviour:

<p>If</p>
show

<p>If with Elsif</p>
show

<p>Unless</p>
show

<p>Case</p>
show
 
<p>Case with When</p>
show

[coveralls]

Pull Request Test Coverage Report for Build 7946818540

Details

• -2 of 27 (92.59%) changed or added relevant lines in 3 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage decreased (-0.09%) to 99.375%

---

Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
src/tags/if.ts	8	10	80.0%

Totals
Change from base Build 7895611436:	-0.09%
Covered Lines:	2261
Relevant Lines:	2270

---

💛 - Coveralls

[harttle]

@all-contributors please add @joel-hamilton for code

[allcontributors]

@harttle

I've put up a pull request to add @joel-hamilton! 🎉

[github-actions]

🎉 This PR is included in version 10.10.1 🎉

The release is available on:

• npm package (@latest dist-tag)
• GitHub release

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