Liquid::Template options are not propagated on new isolated subcontext

[narnd]

Liquid::Context#new_isolated_subcontext should also set the render options strict_variables and strict_filters for the subcontext.

Maybe im missing something but I cant figure out how to raise undefined variable or undefined filter in partials using the render tag.

Please advise, happy to write a pr.

Example:

class PatchedContext < Liquid::Context
  def new_isolated_subcontext
    super.tap do |subcontext|
      subcontext.strict_variables = strict_variables
      subcontext.strict_filters = strict_filters
    end
  end
end

class FileSystem
  def read_template_file(_template_path)
    "{{ undefined_var }}{{ 'test' | undefined_filter }}"
  end
end

# normal example, no errors
liquid_context = Liquid::Context.build(registers: {file_system: FileSystem.new})
template = Liquid::Template.parse("{% render 'partial' %}")
template.render(liquid_context, strict_variables: true, strict_filters: true)
template.errors
# => []

# expected behavior, errors in partial
patched_context = PatchedContext.build(registers: {file_system: FileSystem.new})
template = Liquid::Template.parse("{% render 'partial' %}")
template.render(patched_context, strict_variables: true, strict_filters: true)
template.errors
# =>
# [#<Liquid::UndefinedVariable: Liquid error: undefined variable undefined_var>,
#  #<Liquid::UndefinedFilter: Liquid error: undefined filter undefined_filter>]

[narnd]

To keep the fallback to static_environments we also have to patch try_variable_find_in_environments..

class PatchedContext < Liquid::Context
  # Propagate render options to subcontext
  def new_isolated_subcontext
    super.tap do |subcontext|
      subcontext.strict_variables = strict_variables
      subcontext.strict_filters = strict_filters
    end
  end

  # Also check static environments before raising
  private def try_variable_find_in_environments(key, raise_on_not_found:)
    [ @environments, @static_environments ].each do |environments|
      environments.each do |environment|
        if environment.respond_to?(:key?) && environment.key?(key)
          value = environment[key]

          if value.is_a?(Proc) && environment.respond_to?(:[]=)
            return environment[key] = value.arity == 0 ? value.call : value.call(self)
          else
            return value
          end
        end
      end
    end

    if @strict_variables && raise_on_not_found
      raise Liquid::UndefinedVariable, "undefined variable #{key}"
    end
  end
end

class FileSystem
  def read_template_file(_template_path)
    "{{ undefined_var }}" \
    "{{ 'test' | undefined_filter }}" \
    "{{ var1 }}{{ var2 }}"
  end
end

# normal example, no errors
liquid_context = Liquid::Context.build(
  registers: {file_system: FileSystem.new},
  static_environments: {"var1" => nil, "var2" => "test"}
)
template = Liquid::Template.parse("{% render 'partial' %}")
template.render(liquid_context, strict_variables: true, strict_filters: true)
template.errors
# => []

# expected behavior, errors in partial, static_environments still work as expected
patched_context = PatchedContext.build(
  registers: {file_system: FileSystem.new},
  static_environments: {"var1" => nil, "var2" => "test"}
)
template = Liquid::Template.parse("{% render 'partial' %}")
template.render(patched_context, strict_variables: true, strict_filters: true)
template.errors
# =>
# [#<Liquid::UndefinedVariable: Liquid error: undefined variable undefined_var>,
#  #<Liquid::UndefinedFilter: Liquid error: undefined filter undefined_filter>]