Only compare OS versions if dig was successful

[rdwebdesign]

What does this PR aim to accomplish?:

On the current Debug Log code, if the dig command fails it is impossible to check if the OS is supported, but the log prints an error message saying the OS is unsupported (even when that's not true), like this:

*** [ DIAGNOSING ]: Operating system
[i] dig return code:  10
[i] dig response:  dig: couldn't get address for 'ns1.pi-hole.net': failure
[✗] Distro:  Debian
[✗] Error: Debian is not a supported distro (https://docs.pi-hole.net/main/prerequisites/)

How does this PR accomplish the above?:

Modifying the os_check() function to compare versions only if dig returns without error.
Also, adding a new error message for this case:

*** [ DIAGNOSING ]: Operating system
[i] dig return code:  10
[i] dig response:  dig: couldn't get address for 'ns1.pi-hole.net': failure
[✗] Distro:  Debian
[✗] Error:  dig command failed - Unable to check OS

Link documentation PRs if any are needed to support this PR:
none

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[yubiuser]

As your working on this part of the code, I think the order of the output should be changed in general

*** [ DIAGNOSING ]: Operating system
[i] dig return code:  0
[i] dig response:  "Raspbian=10,11 Ubuntu=20,22 Debian=10,11 Fedora=35,36 CentOS=8,9"
[✓] Distro:  Debian
[✓] Version: 11

I would print Distro/Version first (only with an [i]) then the dig code/return and a new additional line with the result of the comparison.

*** [ DIAGNOSING ]: Operating system
[i] Distro:  Debian
[i] Version: 11
[i] dig return code:  0
[i] dig response:  "Raspbian=10,11 Ubuntu=20,22 Debian=10,11 Fedora=35,36 CentOS=8,9"
[✓] Distro and version supported

[yubiuser]

Current output

*** [ DIAGNOSING ]: Operating system
[✓] Distro:  Debian
[✓] Version: 11
[i] dig return code: 0
[i] dig response: "Raspbian=10,11 Ubuntu=20,22 Debian=10,11 Fedora=35,36 CentOS=8,9"
[✓] Distro and version supported

*** [ DIAGNOSING ]: Operating system
[✓] Distro:  Debian
[✗] Version: 21
[i] dig return code: 0
[i] dig response: "Raspbian=10,11 Ubuntu=20,22 Debian=10,11 Fedora=35,36 CentOS=8,9"
[✗] Error: Debian is supported but version 21 is currently unsupported (https://docs.pi-hole.net/main/prerequisites/)

*** [ DIAGNOSING ]: Operating system
[i] Distro: Debian
[✗] dig return code: 10
[✗] dig response: dig: couldn't get address for 'ns1.pi-hole.net': not found
[✗] Error: dig command failed - Unable to check OS

Applied suggestions

[PromoFaux]

For people here in the future - some sort of oddity happened here in that PR was merged (check dev, the commits are there!) but for some reason it got marked as closed.

Initially it was saying there were merge conflicts that needed to be adjusted on the command line.. and then I just followed the instructions:

• checkout tweak/os_check_error locally
• merge development into it
• resolve conflicts (there were none!)
• push back to tweak/os_check_error

Then github got confused and closed the PR.

75308e4