This has been observed with an old version of PostgreSQL (11.0.4)
running on Windows Server 2016 with windows-1252 encoding and French
locale.

This change replaces invalid UTF-8 fields with a default string, so the
other fields can still be read if they are valid.

…t UTF-8"

This reverts commit 362ca98.

Otherwise, we return the invalid UTF-8 error to avoid panicking later.