fix(common): getRoomItemPoolType handles -1 properly #6689

Job	Run time
get-build-packages	4s
get-lint-packages	7s
get-test-packages	7s
monorepo-lint	1m 22s
build (docs)	33s
build (isaac-lua-polyfill)	56s
build (isaacscript-common)	1m 18s
build (eslint-plugin-isaacscript)	34s
build (isaac-typescript-definitions)	1m 13s
build (isaac-typescript-definitions-repentogon)	29s
build (isaacscript-cli)	33s
lint (docs)	1m 3s
lint (isaacscript-common)	1m 39s
lint (isaacscript-cli)	1m 10s
lint (isaac-typescript-definitions)	1m 7s
lint (eslint-config-isaacscript)	40s
lint (isaacscript-spell)	38s
lint (isaac-lua-polyfill)	1m 6s
lint (isaac-typescript-definitions-repentogon)	1m 7s
lint (eslint-plugin-isaacscript)	1m 17s
test (isaacscript-cli)	54s
test (eslint-plugin-isaacscript)	37s
Discord Failure Notification	5s
	18m 39s

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