fix(M-Pesa): validate type before executing get_doc

[sagarvora]

Type validation must be done before getting the Integration Request.

[codecov]

Codecov Report

Merging #28369 (30cc7a1) into develop (fdb8e18) will decrease coverage by 0.09%.
The diff coverage is 50.00%.

@@             Coverage Diff             @@
##           develop   #28369      +/-   ##
===========================================
- Coverage    55.25%   55.16%   -0.10%     
===========================================
  Files         1119     1119              
  Lines        66538    66553      +15     
===========================================
- Hits         36765    36712      -53     
- Misses       29773    29841      +68     

Impacted Files	Coverage Δ
...egrations/doctype/mpesa_settings/mpesa_settings.py	74.05% <50.00%> (-0.63%)	⬇️
...work_order_stock_report/work_order_stock_report.py	50.00% <0.00%> (-50.00%)	⬇️
erpnext/utilities/product.py	14.70% <0.00%> (-35.30%)	⬇️
erpnext/shopping_cart/product_info.py	30.30% <0.00%> (-21.22%)	⬇️
...payroll/doctype/income_tax_slab/income_tax_slab.py	83.33% <0.00%> (-16.67%)	⬇️
...value/warehouse_wise_item_balance_age_and_value.py	92.40% <0.00%> (-2.54%)	⬇️
...e/shopping_cart_settings/shopping_cart_settings.py	65.38% <0.00%> (-1.93%)	⬇️
...ctype/accounting_dimension/accounting_dimension.py	64.06% <0.00%> (-1.57%)	⬇️
erpnext/shopping_cart/product_query.py	61.19% <0.00%> (-1.50%)	⬇️
...e/period_closing_voucher/period_closing_voucher.py	88.05% <0.00%> (-1.50%)	⬇️
... and 18 more