Sorry, I did notice this MR right away but then I forgot about it until a few minutes ago...
It's legal for well-behaved programs to try to compile invalid shaders, but that should be a rare enough case that it's worth printing it to Wine debug output regardless.
I don't know that it's super rare but, at this point in the HLSL compiler's development, it does seem better to be noisy with errors. We can always turn those ERRs() into WARNs() if / when we feel it's too much.
WRT the patches, I have just a couple of nitpicks and I don't feel too strongly about them either.