Fix language server crash when processing predefind macros. (#2302)
Fix language server crash when processing predefind macros. (#2302)

Co-authored-by: Yong He <6f8726bda63d9802f9f6015cfa021a7333fe9606@nvidia.com>
Co-authored-by: jsmall-nvidia <ba36e50ee2a280bd63d65c073bf01958e3433531@nvidia.com>
shader-slang/slang,shader-slang/slang,csyonghe/slang,csyonghe/slang,csyonghe/slang,shader-slang/slang