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[timostamm]

We didn't mark our package as free from side effects. This shaves off a third of our bundle size in a simple use case.

Code size is now in the expected range - best in class:

code generator	bundle size	minified	compressed
protobuf-es	72,457 b	35,936 b	9,393 b
ts-proto	73,318 b	36,033 b	9,613 b
protobuf-ts	97,516 b	45,850 b	11,452 b
google-protobuf	368,034 b	270,748 b	43,704 b