Handlebars throws IndexOutOfRangeException

[DavidBoike]

Describe the bug

In certain situations, Handlebars will throw an IndexOutOfRangeException. There may be more use cases, but I have isolated one in which the failure is dependent upon the existence of an unused partial template with fairly innocuous contents.

HandlebarsDotNet.HandlebarsRuntimeException : Runtime error while rendering partial 'Navigation', see inner exception for more information
    ---- System.IndexOutOfRangeException : Index was outside the bounds of the array.
  Stack Trace: 
    PartialBinder.InvokePartial(String partialName, BindingContext context, EncodedTextWriter writer, ICompiledHandlebarsConfiguration configuration)
    PartialBinder.InvokePartialWithFallback(String partialName, BindingContext context, EncodedTextWriter writer, ICompiledHandlebarsConfiguration configuration)
    lambda_method(Closure , EncodedTextWriter& , BindingContext )
    <>c__DisplayClass15_0.<Compile>b__0(TextWriter writer, Object context, Object data)
    <>c__DisplayClass16_0.<Compile>b__0(Object context, Object data)
    RenderingWithUnusedPartials.ShouldRender() line 61
    ----- Inner Stack Trace -----
    ArrayIterator`1.Iterate(EncodedTextWriter& writer, BindingContext context, ChainSegment[] blockParamsVariables, Object input, TemplateDelegate template, TemplateDelegate ifEmpty)
    IIterator.Iterate(EncodedTextWriter& writer, BindingContext context, ChainSegment[] blockParamsVariables, Object input, TemplateDelegate template, TemplateDelegate ifEmpty)
    Iterator.Iterate(BindingContext context, EncodedTextWriter writer, ChainSegment[] blockParamsVariables, Object target, TemplateDelegate template, TemplateDelegate ifEmpty)
    lambda_method(Closure , EncodedTextWriter& , BindingContext )
    <>c__DisplayClass15_0.<Compile>b__0(TextWriter writer, Object context, Object data)
    PartialBinder.InvokePartial(String partialName, BindingContext context, EncodedTextWriter writer, ICompiledHandlebarsConfiguration configuration)

Expected behavior:

Should render without throwing.

Test to reproduce

public class RenderingWithUnusedPartial
{
    [Fact]
    public void ShouldRender()
    {
        var handlebars = Handlebars.Create();

        var mainTemplate = @"
{{>Navigation}}
";

        var navPartial = @"
<div>
    {{#each MenuItems}}
    <div>Menu Item: {{Name}}</div>
    {{/each}}
</div>";

        // Remove the {{#if First}} section, and the test will pass
        var unusedPartial = @"
{{#each Results}}
    Result
    {{#if HasSinglePackage}}
        HasSinglePackage
        {{#if First}}
            First
        {{/if}}
    {{/if}}
{{/each}}";

        var navTemplate = handlebars.Compile(mainTemplate);
        Console.WriteLine("Registered template: Navigation");

        using (var reader = new StringReader(navPartial))
        {
            handlebars.RegisterTemplate("Navigation", handlebars.Compile(reader));
            Console.WriteLine("Registered partial: Navigation ");
        }

        // Comment this section out and the test will succeed
        using (var reader = new StringReader(unusedPartial))
        {
            handlebars.RegisterTemplate("Unused", handlebars.Compile(reader));
            Console.WriteLine("Registered partial: Unused ");
        }

        // Attempted with concrete classes, still fails
        var context = new
        {
            MenuItems = new[]
            {
                    new { Name = "Getting Started"}
                }
        };

        var transformed = navTemplate(context).Trim();

        Assert.Equal(@"<div>
    <div>Menu Item: Getting Started</div>
</div>", transformed);
    }
}

Other related info

• Tested in 2.0.1
• Tested using netcoreapp3.1 and net5.0 target frameworks

[DavidBoike]

Thank you @zjklee - 2.0.2 works!