I found your answers very useful, so I took the liberty of publishing them on the thread I opened about the problem on the internet ( https://stackoverflow.com/a/59922553/3223785 ).
If you do not want this content to continue to be published, please let me know so I can delete it.
Thanks for the suggestions! I found it a bit strange "pgsql" not to "understand" as an exception the "ERROR: missing chunk number 0 for toast value 3483039 in pg_toast_3473493"
Please inline or bottom-post here.
I think Tom's point is that the function you wrote never actually attempted to print out the value of the field so the error never got triggered in the function. You need to actually attempt to manipulate the data to get an error. If you did get the function to actually encounter the error it should (haven't tested myself) be caught in the exception handler; i.e., "A more reliable way to trigger the problem is to do some computation
that requires the value of the field, perhaps along the lines of [query to try]".