Spurious redundant match diagnostic

[robertoaloi]

Describe the bug

To Reproduce**

Given the following code:

-module(test).

-export([main/1]).

main(X) ->
    case X of
        a ->
            Foo = foo,
    %% ^^^ Warning: Match is redundant
            Bar =
                case undefined of
                    undefined -> undefined
                end;
        b ->
            Foo = bar,
            Bar = baz
    end,
    #{
        foo => Foo,
        bar => Bar
    }.

Expected behavior

No diagnostics are produced.

Actual behavior

An incorrect W0007 diagnostic is reported on Foo.