Fix purchase order import form

InvenTree/common/files.py

@@ -99,13 +99,18 @@ class FileManager:
         self.update_headers()
 
     def guess_header(self, header, threshold=80):
-        """ Try to match a header (from the file) to a list of known headers
+        """
+        Try to match a header (from the file) to a list of known headers
 
         Args:
             header - Header name to look for
             threshold - Match threshold for fuzzy search
         """
 
+        # Replace null values with empty string
+        if header is None:
+            header = ''
+
         # Try for an exact match
         for h in self.HEADERS:
             if h == header:

InvenTree/order/templates/order/order_base.html

@@ -145,10 +145,6 @@ src="{% static 'img/blank_image.png' %}"
 {% block js_ready %}
 {{ block.super }}
 
-enableNavbar({
-    label: 'po',
-    toggleId: '#po-menu-toggle',
-});
 
 {% if order.status == PurchaseOrderStatus.PENDING and order.lines.count > 0 %}
 $("#place-order").click(function() {

InvenTree/order/templates/order/order_wizard/po_upload.html

@@ -3,10 +3,6 @@
 {% load i18n %}
 {% load static %}
 
-{% block menubar %}
-{% include 'order/po_navbar.html' with tab='upload' %}
-{% endblock %}
-
 {% block heading %}
 {% trans "Upload File for Purchase Order" %}
 {{ wizard.form.media }}

InvenTree/order/templates/order/purchase_order_detail.html

@@ -77,6 +77,11 @@
 
 {{ block.super }}
 
+    enableNavbar({
+        label: 'po',
+        toggleId: '#po-menu-toggle',
+    });
+
     $('#edit-notes').click(function() {
         constructForm('{% url "api-po-detail" order.pk %}', {
             fields: {