fix: Initialise pending qty as planned qty for independent item rows in Prod Plan

- Rows that are not fetched from MR or SO, had pending qty 0 throughout
- Initialise pending qty on save only.
- After submit this field will be updated by work order/stock entry
- Bring functions in `validate()` closer to the top

(cherry picked from commit eaccef6116)

erpnext/manufacturing/doctype/production_plan/production_plan.py

@@ -29,9 +29,24 @@ from erpnext.setup.doctype.item_group.item_group import get_item_group_defaults
 
 class ProductionPlan(Document):
 	def validate(self):
+		self.set_pending_qty_in_row_without_reference()
 		self.calculate_total_planned_qty()
 		self.set_status()
 
+	def set_pending_qty_in_row_without_reference(self):
+		"Set Pending Qty in independent rows (not from SO or MR)."
+		if self.docstatus > 0: # set only to initialise value before submit
+			return
+
+		for item in self.po_items:
+			if not item.get("sales_order") or not item.get("material_request"):
+				item.pending_qty = item.planned_qty
+
+	def calculate_total_planned_qty(self):
+		self.total_planned_qty = 0
+		for d in self.po_items:
+			self.total_planned_qty += flt(d.planned_qty)
+
 	def validate_data(self):
 		for d in self.get('po_items'):
 			if not d.bom_no:
@@ -264,11 +279,6 @@ class ProductionPlan(Document):
 						'qty': so_detail['qty']
 				})
 
-	def calculate_total_planned_qty(self):
-		self.total_planned_qty = 0
-		for d in self.po_items:
-			self.total_planned_qty += flt(d.planned_qty)
-
 	def calculate_total_produced_qty(self):
 		self.total_produced_qty = 0
 		for d in self.po_items: