fix: error in linking lessons on course page

The course was adding `{{ no such element: community.lms.doctype.lms_course.lms_course.LMSCourse object['query_parameter'] }}`
to the lesson links. Fixed it by setting query_parameter to "".

community/lms/doctype/lms_batch_membership/lms_batch_membership.py

@@ -32,20 +32,28 @@ class LMSBatchMembership(Document):
             frappe.throw(_("{0} is already a {1} of the course {2}").format(member_name, previous_membership.member_type, course_title))
 
     def validate_membership_in_different_batch_same_course(self):
+        """Ensures that a studnet is only part of one batch.
+        """
+        # nothing to worry if the member is not a student
+        if self.member_type != "Student":
+            return
+
         course = frappe.db.get_value("LMS Batch", self.batch, "course")
-        previous_membership = frappe.get_all("LMS Batch Membership",
+        memberships = frappe.get_all(
+            "LMS Batch Membership",
             filters={
                 "member": self.member,
-                                        "name": ["!=", self.name]
+                "name": ["!=", self.name],
+                "member_type": "Student",
+                "course": self.course
             },
             fields=["batch", "member_type", "name"]
         )
 
-        for membership in previous_membership:
+        if memberships:
-            batch_course = frappe.db.get_value("LMS Batch", membership.batch, "course")
+            membership = memberships[0]
-            if batch_course == course and (membership.member_type == "Student" or self.member_type == "Student"):
             member_name = frappe.db.get_value("User", self.member, "full_name")
-                frappe.throw(_("{0} is already a {1} of {2} course through {3} batch").format(member_name, membership.member_type, course, membership.batch))
+            frappe.throw(_("{0} is already a Student of {1} course through {2} batch").format(member_name, course, membership.batch))
 
 @frappe.whitelist()
 def create_membership(course, batch=None, member=None, member_type="Student", role="Member"):

community/lms/md.py

@@ -36,6 +36,8 @@ def find_macros(text):
             ('Exercise', 'four-circles')
         ]
     """
+    if not text:
+        return []
     macros = re.findall(MACRO_RE, text)
     # remove the quotes around the argument
     return [(name, _remove_quotes(arg)) for name, arg in macros]

community/www/courses/course.py

@@ -16,6 +16,7 @@ def get_context(context):
         raise frappe.Redirect
 
     context.course = course
+    context.course.query_parameter = ""
     if not course.is_mentor(frappe.session.user):
         batch = course.get_membership(frappe.session.user)
         if batch: