Improved error handling and one fix in order to detect #1103 issues

Take a look at this, @Kartones . This is mostly error handling improvements, including some deleted error shallowing that might be responsible of not detecting what's happening under the hood. On one hand more errors will be shown, but on the other mail won't send a not working, success link, and we should be able to see better logs.
I'm worried about some syncs failing now. Importer had some unoptimal code that did things like "try to do this, if fails silently recover and keep going".

We can leave it be, but this need a full smoke test regarding everything that manipulates tables, from imports to merges, duplication, etc., because I've been "hit" in the past by unexpected errors due to this silent try catches.


An alternative would be logging the error and as much detailed info as possible, so we don't change the importer to now fail there, but we register the new errors.