Fix LastStores::update for stores without an alias region#13512

fitzgen merged 2 commits into

bytecodealliance:mainbytecodealliance/wasmtime:mainfrom

fitzgen:issue-135080-differential-fuzz-failure-after-alias-regionsfitzgen/wasmtime:issue-135080-differential-fuzz-failure-after-alias-regionsCopy head branch name to clipboard