Show empty state when no students are found in student attendance tool (#8862)

- fixes #8839
diff --git a/erpnext/schools/doctype/student_attendance_tool/student_attendance_tool.js b/erpnext/schools/doctype/student_attendance_tool/student_attendance_tool.js
index b092a3f..6f8c6cd 100644
--- a/erpnext/schools/doctype/student_attendance_tool/student_attendance_tool.js
+++ b/erpnext/schools/doctype/student_attendance_tool/student_attendance_tool.js
@@ -47,7 +47,7 @@
 			frm.students_area = $('<div>')
 				.appendTo(frm.fields_dict.students_html.wrapper);
 		}
-		console.log(students);
+		students = students || [];
 		frm.students_editor = new schools.StudentsEditor(frm, frm.students_area, students)
 	}
 });
@@ -57,7 +57,11 @@
 	init: function(frm, wrapper, students) {
 		this.wrapper = wrapper;
 		this.frm = frm;
-		this.make(frm, students);
+		if(students.length > 0) {
+			this.make(frm, students);
+		} else {
+			this.show_empty_state();
+		}
 	},
 	make: function(frm, students) {
 		var me = this;
@@ -159,5 +163,13 @@
 		});
 
 		$(htmls.join("")).appendTo(me.wrapper);
+	},
+
+	show_empty_state: function() {
+		$(this.wrapper).html(
+			`<div class="text-center text-muted" style="line-height: 100px;">
+				${__("No Students in")} ${this.frm.doc.student_group}
+			</div>`
+		);
 	}
 });
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