fix: validate negative quantity for sample collection

erpnext/healthcare/doctype/sample_collection/sample_collection.py

@@ -3,7 +3,12 @@
 # For license information, please see license.txt
 
 from __future__ import unicode_literals
+import frappe
 from frappe.model.document import Document
+from frappe.utils import flt
+from frappe import _
 
 class SampleCollection(Document):
-	pass
+	def validate(self):
+		if flt(self.sample_qty) <= 0:
+			frappe.throw(_('Sample Quantity cannot be negative or 0'), title=_('Invalid Quantity'))