`isInSubnet` not throwing on invalid subnets

[Spencer Wilson]

The isInSubnet docs state

Will throw an Error if the address or subnet are not valid IP addresses

but some subnets with invalid IP address components do not cause the function to throw. Here are an examples with an IPv4-like thing and IPv6-like thing:

> isIP('1.352352352')
0
> isInSubnet('1.3.3.4', '1.352352352/32')
false
> isIP('11:22:33:44:55:66:77:88:99:1010')
0
> isInSubnet('1.3.3.4', '11:22:33:44:55:66:77:88:99:1010/32')
false

Notably, the specialized functions IPv4.isInSubnet and IPv6.isInSubnet don't exhibit issue:

> IPv4.isInSubnet('1.3.3.4', '1.352352352/32')
Thrown:
Error: not a valid IPv4 address: 1.352352352
> IPv6.isInSubnet('::ffff:1.2.3.4', '11:22:33:44:55:66:77:88:99:1010/32')
Thrown:
Error: not a valid IPv6 address: 11:22:33:44:55:66:77:88:99:1010

P.S. Thank you for writing such a well-documented and single-purpose package!