fix flake8 F841 (local variable is assigned to but never used)

lnbits/extensions/lnurlp/crud.py

@@ -46,6 +46,7 @@ async def create_pay_link(data: CreatePayLinkData, wallet_id: str) -> PayLink:
             data.fiat_base_multiplier,
         ),
     )
+    assert result
 
     link = await get_pay_link(link_id)
     assert link, "Newly created link couldn't be retrieved"

lnbits/extensions/subdomains/tasks.py

@@ -54,5 +54,6 @@ async def on_invoice_paid(payment: Payment) -> None:
                     },
                     timeout=40,
                 )
+                assert r
             except AssertionError:
                 pass