fix: call to (*T).Fatal from a non-test goroutine

[haton14]

Thanks for the great library. Although not a direct contribution to the functionality, I have fixed the test functions.

Reference:

• https://github.com/ipfs/kubo/issues/2043#issuecomment-164136026
• https://go.dev/ref/spec#Break_statements

[pikanezi]

Thanks!