improve eslint config and fix some lint errors #768

Job	Run time
benchmark-build	54s
yjs-lib-test	56s
lib-site-build	1m 27s
lib-test (tsc - mobx6)	1m 18s
lib-test (tsc - mobx5)	1m 8s
lib-test (tsc - mobx4)	1m 6s
lib-test (tsc-experimental-decorators - mobx6)	1m 5s
lib-test (tsc-experimental-decorators - mobx5)	1m 12s
lib-test (tsc-experimental-decorators - mobx4)	1m 7s
lib-test (babel - mobx6)	55s
lib-test (babel - mobx5)	53s
lib-test (babel - mobx4)	59s
lib-test (swc - mobx6)	56s
lib-test (swc - mobx5)	54s
lib-test (swc - mobx4)	53s
	15m 43s

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