-e: see title, build works when adding a specific memory size
--this is a regression in emscripten itself

-repro:
--open attached project
--build&run for webgl
--notice it works
--open Editor\EnableThreads.cs
--remove "PlayerSettings.WebGL.memorySize = 512;"
--recompile
--build and run
--NOTICE build fails in browser with error:

Cannot enlarge memory arrays. Either (1) compile with -s TOTAL_MEMORY=X with X higher than the current value 16777216, (2) compile with -s ALLOW_MEMORY_GROWTH=1 which allows increasing the size at runtime, or (3) if you want malloc to return NULL (0) instead of this abort, compile with -s ABORTING_MALLOC=0