[FIX] sms: fix crash when using composer on a record without valid phone number

When no valid phone number was found on a record, and when using the composer
in single recipient mode, you had a crash at sending as composer tried to
write on a field called False.

Instead we just take the first available phone field of the record. As they
are all void we can update them safely.

Task ID 2244192

X-original-commit: 2306d7d79d8e64597912f15365cede7473589731