fix: check item_code in all rows of po_items

[s-aga-r]

Source / Reference: ISS-22-23-01552

There can be rows which do not have item-code selected in po-items. Check all rows for item-code in po_items before fetching the sub-assembly items, throw an error if not available.

[codecov[bot]]

Codecov Report

Merging #31741 (a6a8c28) into develop (5018472) will decrease coverage by 0.36%. The diff coverage is 50.00%.

:exclamation: Current head a6a8c28 differs from pull request most recent head 5277523. Consider uploading reports for the commit 5277523 to get more accurate results

@@             Coverage Diff             @@
##           develop   #31741      +/-   ##
===========================================
- Coverage    63.45%   63.08%   -0.37%     
===========================================
  Files          813      813              
  Lines        57531    57527       -4     
===========================================
- Hits         36507    36292     -215     
- Misses       21024    21235     +211     

Impacted Files	Coverage Δ
...cturing/doctype/production_plan/production_plan.py	74.86% <50.00%> (-0.09%)	:arrow_down:
...eport/item_variant_details/item_variant_details.py	31.32% <0.00%> (-53.02%)	:arrow_down:
...unts/report/purchase_register/purchase_register.py	34.21% <0.00%> (-42.77%)	:arrow_down:
.../report/delayed_item_report/delayed_item_report.py	60.78% <0.00%> (-35.30%)	:arrow_down:
...tch_item_expiry_status/batch_item_expiry_status.py	67.92% <0.00%> (-24.53%)	:arrow_down:
...wise_balance_history/batch_wise_balance_history.py	67.79% <0.00%> (-22.04%)	:arrow_down:
...ext/accounts/report/balance_sheet/balance_sheet.py	36.36% <0.00%> (-21.82%)	:arrow_down:
...e_purchase_register/item_wise_purchase_register.py	57.42% <0.00%> (-19.81%)	:arrow_down:
erpnext/accounts/doctype/bank/bank.py	71.42% <0.00%> (-14.29%)	:arrow_down:
...em_wise_sales_register/item_wise_sales_register.py	50.45% <0.00%> (-10.46%)	:arrow_down:
... and 30 more