This condition will always return 'false' since the types 'false' and 'true' have no overlap

Issue Type: Bug

inst.getCartItems(function(items :any){
        var item_found = false;
        items = items.map(function(item:any){
          if(item.product_id == product_id){
            item_found = true;
            item.quantity = item.quantity+quantity;
          }
          return item;
        });

       //This condition will always return 'false' since the types  'false' and 'true' have no overlap
        if(item_found == true){
            items.push({
              product_id : product_id,
              quantity : quantity
            });
        }
        localStorage.setItem("cart",JSON.stringify(items));
      });

seems validator is not detecthing variable scrope inside map function

Extension version: 0.4.0 VS Code version: Code 1.54.3 (2b9aebd5354a3629c3aba0a5f5df49f43d6689f8, 2021-03-15T10:55:45.459Z) OS version: Windows_NT x64 10.0.19042

System Info

|Item|Value| |---|---| |CPUs|AMD Ryzen 5 3550H with Radeon Vega Mobile Gfx (8 x 2096)| |GPU Status|2d_canvas: enabled
gpu_compositing: enabled
multiple_raster_threads: enabled_on
oop_rasterization: enabled
opengl: enabled_on
protected_video_decode: enabled
rasterization: enabled
skia_renderer: enabled_on
video_decode: enabled
vulkan: disabled_off
webgl: enabled
webgl2: enabled| |Load (avg)|undefined| |Memory (System)|7.69GB (2.40GB free)| |Process Argv|--crash-reporter-id 78883d0f-eda4-4725-a7a0-cb18b15554c9| |Screen Reader|no| |VM|0%|

A/B Experiments

``` vsliv368cf:30146710 vsreu685:30147344 python383:30185418 pythonvspyt700cf:30270857 vspor879:30202332 vspor708:30202333 vspor363:30204092 vswsl492cf:30256860 vstry244:30276681 pythonvsdeb440:30248342 pythonvsded773:30248341 vstes516:30244333 pythonvspyt875:30259475 pythonvsnew554:30281908 pythontbcf:30265426 pythonvspyt943:30280189 openwsldoc:30282072 vspre833:30267464 pythonptprofiler:30281270 vshan820cf:30276953 ```

eamodio / vscode-tsl-problem-matcher

This condition will always return 'false' since the types 'false' and 'true' have no overlap #8