Yeah... Although a 17MB log file is not really a joy.
Anyway: 2019-12-15 19:28:03.926 T:1807721344 NOTICE: MYSQL: Connected to version 5.5.62-MariaDB
That's a pretty old version... Any chance you can upgrade it to something more contemporary?
I see several of this one: ERROR: SQL: Missing result set!
But I don't see a query going wrong.
You could also enable the Database component in the logging options.
2019-12-15 19:29:09.848 T:1593762688 ERROR: GetSingleValue - failed on query 'SELECT count(1) FROM movie_view LIMIT 1'
2019-12-15 19:29:09.890 T:1593762688 ERROR: GetSingleValue - failed on query 'SELECT count(playCount) FROM movie_view LIMIT 1'
You may have a corrupted database.
Can you check which tables and views are present on your database server?
And all the 'spam' in your log...
NOTICE: ADDON: skin.estuary.modv2 v3.0.5 installed
It's a skin with lots of added 'features' but the whole package also has been pretty unstable IMO.
Change to the default Estuary skin and restart LibreELEC before providing a new log file.