Compiler crash on generic comparable tuples in let-bindings

[sergey-salnikov]

Elm version: 0.19.0
OS: Linux, Ubuntu 18.04

Compiler crashes on the following code

module Main exposing (f)


f : comparable -> Bool
f x =
    let
        result =
            ( 0, x ) < ( 1, x )
    in
    result

Error message is the same as in #1748:

$ elm make src/Main.elm
elm: ./Data/Vector/Generic/Mutable.hs:703 (modify): index out of bounds (3,3)
CallStack (from HasCallStack):
  error, called at ./Data/Vector/Internal/Check.hs:87:5 in vector-0.12.0.1-IfIQAgrX0q07Xkx6bkYLRX:Data.Vector.Internal.Check
elm: thread blocked indefinitely in an MVar operation

Adding concrete top-level type (f : Int -> Bool) or subannotation (result : Bool) avoids the crash.