I edited slightly the original code and added some comments.
-------------------------------------------------------------------------------------------tell application "Contacts"
tell group "Famille"
set phoneNumList to value of every phone of every person
end tell
end tell
try
phoneNumList / 0 # Issue an error message
on error e
# Here e is the error message
(*
"Impossible de convertir {{\"0645914322\"}, {}, {\"06 46 60 33 66\", \"06 45 24 95 66\"}, {\"00 (1) 605 532 66 23\"}, {}, {}, {\"06 26 19 63 14\"}, {\"02 33 66 53 15\", \"06 32 26 56 10\"}, {\"06 92 09 96 92\"}, {\"06 93 63 96 40\", \"06 26 13 60 65\"}, {}, {}, {\"03 56 96 96 04\", \"06 61 55 31 60\"}, {\"01 66 62 11 15\", \"06 10 01 05 00\"}, {\"06 93 44 06 62\"}, {\"06 55 60 09 66\"}, {\"01 65 51 29 06\", \"06 26 61 53 43\", \"01 36 56 56 50\"}, {}, {}, {\"06 46 52 05 29\"}, {\"06 49 56 09 39\"}, {\"02 33 04 93 94\"}} en type real."
*)
set shCMD to "echo " & quoted form of e & " | tr '\"' '\\n' | sed -En '/[0-9]/p'"
# The command will extract the phone numbers from the error message
set phoneNumList to paragraphs of (do shell script shCMD)
end try
-------------------------------------------------------------------------------------------
It behaves flawlessly.
Yvan KOENIG running Sierra 10.12.2 in French (VALLAURIS, France) jeudi 5 janvier 2017 19:44:42