Problems view doesn't report TypeScript unreachable code

[jonchardy]

Issue Type: Bug

1. Set "typescript.reportStyleChecksAsWarnings": false so that unreachable code is an error.
2. Create a simple file:

function test(): boolean {
  return true;
  return false;
}

test();

The return false line is greyed out and upon hover shows the TS error, but the problems view doesn't report it. It also causes an error during compilation.

VS Code version: Code 1.25.1 (1dfc5e5, 2018-07-11T15:43:53.668Z)
OS version: Windows_NT x64 10.0.17134

System Info

Item	Value
CPUs	Intel(R) Core(TM) i7-8650U CPU @ 1.90GHz (8 x 2112)
GPU Status	2d_canvas: enabled flash_3d: enabled flash_stage3d: enabled flash_stage3d_baseline: enabled gpu_compositing: enabled multiple_raster_threads: enabled_on native_gpu_memory_buffers: disabled_software rasterization: disabled_software video_decode: enabled video_encode: enabled vpx_decode: enabled webgl: enabled webgl2: enabled
Memory (System)	31.84GB (23.18GB free)
Process Argv	C:\Program Files\Microsoft VS Code\Code.exe
Screen Reader	no
VM	0%

Extensions: none

[mjbvz]

This matches the behavior of tsc. Unreachable code is not reported as an error (hence shown in problems) unless you set allowUnreachableCode": false or "strict": true in your tsconfig.json

[jonchardy]

Ok, figured out the problem. Our tsconfig is nested in a config folder, so allowUnreachableCode wasn't being accounted for properly. Looks like another use case for #12463, since we have different files named tsconfig in different folders.