ipfs-cluster-ctl should not return error code 0 in case of incorrect usage

[gdethier]

Additional information:

• OS: Ubuntu 21.10
• IPFS Cluster version: 0.14.5
• Installation method: dist.ipfs.io

Describe the bug:
When calling ipfs-cluster-ctl with invalid arguments (e.g. ipfs-cluster-ctl add some-file.txt -rmin NaN), an error message is shown (e.g. Incorrect Usage: invalid value "NaN" for flag -rmin: parse error) followed by the program's usage string. In that case, the error code is 0 and everything is output to stdout.

I would expect a return code different from 0, which is particularly important if you use that command in a script.

I see that error codes 1 and 2 are already in use but for another purpose (#178), maybe add an error code 3 for input related issues?

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[hsanjuan]

Thank you, indeed per the docs it should return with 1 (argument error).