Fixed nim-lang#8399 (nim-lang#8401)

compiler/closureiters.nim

@@ -588,7 +588,7 @@ proc lowerStmtListExprs(ctx: var Ctx, n: PNode, needsSplit: var bool): PNode =
           let branch = n[i]
           case branch.kind
           of nkOfBranch:
-            branch[1] = ctx.convertExprBodyToAsgn(branch[1], tmp)
+            branch[^1] = ctx.convertExprBodyToAsgn(branch[^1], tmp)
           of nkElse:
             branch[0] = ctx.convertExprBodyToAsgn(branch[0], tmp)
           else:

tests/async/tasync_misc.nim

@@ -0,0 +1,47 @@
+discard """
+  exitcode: 0
+  output: "ok"
+"""
+
+import json, asyncdispatch
+block: #6100
+  let done = newFuture[int]()
+  done.complete(1)
+
+  proc asyncSum: Future[int] {.async.} =
+    for _ in 1..10_000_000:
+      result += await done
+
+  let res = waitFor asyncSum()
+  doAssert(res == 10000000)
+
+block: #7985
+  proc getData(): Future[JsonNode] {.async.} =
+    result = %*{"value": 1}
+
+  type
+    MyData = object
+      value: BiggestInt
+
+  proc main() {.async.} =
+    let data = to(await(getData()), MyData)
+    doAssert($data == "(value: 1)")
+
+  waitFor(main())
+
+block: #8399
+  proc bar(): Future[string] {.async.} = discard
+
+  proc foo(line: string) {.async.} =
+    var res =
+      case line[0]
+      of '+', '-': @[]
+      of '$': (let x = await bar(); @[""])
+      else:
+        nil
+
+    doAssert(res == @[""])
+
+  waitFor foo("$asd")
+
+echo "ok"