Looking for online databases or printed compilations of launch vehicle accidents, mistakes done while fabricating rockets and preventive measure taken.
One resource is the NASA page "Launch Vehicle History"
Individual failures (click on the small red squares in the timelines) have reports and sources linked, though the level of detail varies wildly.
Another resource is the NASA page "Significant Incidents & Close Calls in Human Spaceflight"
This has a couple of reports available for each listed incident. They are grouped by which part of the mission the incident happened, so you would want the "ascent" part.
Limited to US and Russian crewed spaceflight.