Fix Sentry issue COMPILER-EXPLORER-1FZ
Fix Sentry issue COMPILER-EXPLORER-1FZ

By changing lastResult default value to `{}` it won't complain
if we try to access one of its children if somehow we don't edit it
beforehand.

@jaredwy can you check that this is indeed not breaking something
unexpected? I'm only 98% sure. That 2% worries me a bit

dkm/gcc-explorer,dkm/gcc-explorer,mattgodbolt/compiler-explorer,mattgodbolt/gcc-explorer,dkm/gcc-explorer,mattgodbolt/compiler-explorer,mattgodbolt/gcc-explorer,mattgodbolt/compiler-explorer,dkm/gcc-explorer,mattgodbolt/gcc-explorer,mattgodbolt/compiler-explorer,mattgodbolt/compiler-explorer,mattgodbolt/gcc-explorer,dkm/gcc-explorer,dkm/gcc-explorer,mattgodbolt/gcc-explorer,dkm/gcc-explorer,mattgodbolt/compiler-explorer,mattgodbolt/compiler-explorer,mattgodbolt/compiler-explorer,dkm/gcc-explorer,dkm/gcc-explorer