[minor] return '' if template is none & ignore if _custom_html field has no options (#3664)

frappe/templates/print_formats/standard_macros.html

@@ -1,7 +1,7 @@
 {% macro render_field(df, doc) -%}
 	{%- if df.fieldtype=="Table" -%}
 		{{ render_table(df, doc) }}
-	{%- elif df.fieldtype=="HTML" -%}
+	{%- elif df.fieldtype=="HTML" and df.options -%}
 		<div>{{ frappe.render_template(df.options, {"doc": doc}) or "" }}</div>
 	{%- elif df.fieldtype in ("Text", "Text Editor", "Code") -%}
 		{{ render_text_field(df, doc) }}

frappe/utils/jinja.py

@@ -57,6 +57,9 @@ def render_template(template, context, is_path=None):
 	:param context: dict of properties to pass to the template
 	:param is_path: (optional) assert that the `template` parameter is a path'''
 
+	if not template:
+		return ""
+
 	# if it ends with .html then its a freaking path, not html
 	if (is_path
 		or template.startswith("templates/")