Fix metadata format error checking (#16036)
Fix metadata format error checking (#16036)

NextStream_Verify can return NULL for invalid file. Report error for it instead of AVing.
Similar check is around the other calls to NextStream_Verify. It was missing here for some reason.
cshung/coreclr,ruben-ayrapetyan/coreclr,ruben-ayrapetyan/coreclr,krk/coreclr,mmitche/coreclr,mmitche/coreclr,yizhang82/coreclr,poizan42/coreclr,yizhang82/coreclr,yizhang82/coreclr,poizan42/coreclr,mmitche/coreclr,ruben-ayrapetyan/coreclr,krk/coreclr,mmitche/coreclr,mmitche/coreclr,poizan42/coreclr,wtgodbe/coreclr,yizhang82/coreclr,ruben-ayrapetyan/coreclr,cshung/coreclr,poizan42/coreclr,wtgodbe/coreclr,wtgodbe/coreclr,krk/coreclr,mmitche/coreclr,krk/coreclr,cshung/coreclr,wtgodbe/coreclr,wtgodbe/coreclr,poizan42/coreclr,yizhang82/coreclr,ruben-ayrapetyan/coreclr,yizhang82/coreclr,ruben-ayrapetyan/coreclr,cshung/coreclr,poizan42/coreclr,cshung/coreclr,krk/coreclr,cshung/coreclr,wtgodbe/coreclr,krk/coreclr