fix(@desktop/wallet): Fix for freeze in Approval stage in SwapModal

noticed only on linux

fixes #18627

Author: Khushboo-dev-cpp

src/app_service/service/transaction/async_tasks.nim

@@ -36,3 +36,19 @@ proc fetchDecodedTxDataTask*(argEncoded: string) {.gcsafe, nimcall.} =
   except Exception as e:
     error "Error decoding tx input", message = e.msg
   arg.finish(data)
+
+type
+  ReevaluateRouterPathTaskArg* = ref object of QObjectTaskArg
+    uuid: string
+    pathName: string
+    chainId: int
+    isApprovalTx: bool
+
+proc reevaluateRouterPathTask*(argEncoded: string) {.gcsafe, nimcall.} =
+  let arg = decode[ReevaluateRouterPathTaskArg](argEncoded)
+  try:
+    let err = wallet.reevaluateRouterPath(arg.uuid, arg.pathName, arg.chainId, arg.isApprovalTx)
+    if err.len > 0:
+      raise newException(CatchableError, err)
+  except CatchableError as e:
+    error "reevaluateRouterPath", exception=e.msg

src/app_service/service/transaction/service.nim

@@ -543,10 +543,12 @@ proc sendRouterTransactionsWithSignatures*(self: Service, uuid: string, signatur
   return ""
 
 proc reevaluateRouterPath*(self: Service, uuid: string, pathName: string, chainId: int, isApprovalTx: bool): string =
-  try:
-    let err = wallet.reevaluateRouterPath(uuid, pathName, chainId, isApprovalTx)
-    if err.len > 0:
-      raise newException(CatchableError, err)
-  except CatchableError as e:
-    error "reevaluateRouterPath", exception=e.msg
-    return e.msg
+  let arg = ReevaluateRouterPathTaskArg(
+    tptr: reevaluateRouterPathTask,
+    vptr: cast[uint](self.vptr),
+    uuid: uuid,
+    pathName: pathName,
+    chainId: chainId,
+    isApprovalTx: isApprovalTx,
+  )
+  self.threadpool.start(arg)