fix: Raise Error on over receipt/consumption for sub-contracted PR

[marination]

Issue:

• Create a sub contracted Purchase Order

• Create two Draft Purchase Receipts that fully receive this very PO

• Submit the Receipts one by one. The first receipt should receive/consume the PO items/supplied items fully

• The second receipt will break as there is no fg_yet_to_be_received (Finish goods yet to be received) in the PO:

    File ".../apps/erpnext/erpnext/controllers/buying_controller.py", line 301, in 
    update_raw_materials_supplied_based_on_stock_entries
         qty = (rm_qty_to_be_consumed / fg_yet_to_be_received) * item.qty
   TypeError: unsupported operand type(s) for /: 'float' and 'NoneType'
  

• This happens on backflush based on materials transferred for subcontracting

Fix:

• Alert the user that an over receipt is taking place as this issue often occurs due to two different users creating PRs against the same PO
  
• While looping if there's no PO against this item (accidentally or intentionally) don't proceed to create any qty maps as they will all be empty

Note

• There is still one problematic case not handled here i.e. Returning a sub-contracted Purchase Receipt. That will be done in a separate PR after more clarity in it's design

[marination]