fix: filter type for item query (#25942)

diff --git a/erpnext/controllers/queries.py b/erpnext/controllers/queries.py
index 638503e..81ac234 100644
--- a/erpnext/controllers/queries.py
+++ b/erpnext/controllers/queries.py
@@ -4,6 +4,7 @@
 from __future__ import unicode_literals
 import frappe
 import erpnext
+import json
 from frappe.desk.reportview import get_match_cond, get_filters_cond
 from frappe.utils import nowdate, getdate
 from collections import defaultdict
@@ -198,6 +199,9 @@
 def item_query(doctype, txt, searchfield, start, page_len, filters, as_dict=False):
 	conditions = []
 
+	if isinstance(filters, str):
+		filters = json.loads(filters)
+
 	#Get searchfields from meta and use in Item Link field query
 	meta = frappe.get_meta("Item", cached=True)
 	searchfields = meta.get_search_fields()