anvil.server.RuntimeUnavailableError: Internal server error: Server runtime failed to pull at Homepage, line 13

What I’m trying to do:
My app was working fine till now but it has started to throw above error
What I’ve tried and what’s not working:
I am completely new to dev so cant figure out whats wrong
Code Sample:

from ._anvil_designer import HomepageTemplate
from anvil import *
import anvil.tables as tables
import anvil.tables.query as q
from anvil.tables import app_tables
import anvil.server
import anvil.media

class Homepage(HomepageTemplate):
  def __init__(self, **properties):
    # Any code you write here will run when the form opens.  
    # Set Form properties and Data Bindings.
    self.my_list = anvil.server.call('get_districts')
    self.init_components(**properties)
 

  def drop_down_1_change(self, **event_args):
    selected_district = self.drop_down_1.selected_value
    if selected_district:
      dataset = anvil.server.call("get_district_data", selected_district)
      #open_form("Form2", district=selected_district, district_data=dataset)
      #self.repeating_panel_1.items=dataset
      #print(dataset)
      total_records = 0
      count_Samagra_total = 0
      count_Samagra=0
      count_KGBV=0
      count_PMSHRI = 0
      for key in dataset:
        total_records =total_records+1
        if (dataset[total_records-1]['SubCategory'])=="PM SHRI":
          count_PMSHRI=count_PMSHRI+1
        elif (dataset[total_records-1]['SubCategory'])=="Samagra":
          count_Samagra =count_Samagra+1
        elif (dataset[total_records-1]['SubCategory'])=="KGBV" :
          count_KGBV = count_KGBV+1       
          
      count_Samagra_total = count_KGBV + count_Samagra    
      self.column_panel_3.visible=1
      self.label_3.text="Total Schools: " + str(total_records)
      self.label_4.text="Total Samagra Schools: " + str(count_Samagra_total) + " (" + "Samagra = " + str(count_Samagra) + " & KGBV = " + str(count_KGBV) + ")"
      self.label_5.text= "Total PM SHRI Schools: " + str(count_PMSHRI)
    
      self.repeating_panel_1.items=dataset
      self.column_panel_2.visible=1
      self.repeating_panel_1.raise_event("x-refresh")

  def button_1_click(self, **event_args):
    """This method is called when the button is clicked"""
    selected_district = self.drop_down_1.selected_value
    csv = anvil.server.call("generate_custom_csv",selected_district)
    #print(csv)
    anvil.media.download(csv)