Correct.
Remove error_handler and fix bugs
These don't cause any problems so they are not really bugs. PHP just decided to report something that might be a problem (but it is not in the case of Adminer).
Link to latest is broken
messageQuery gets this info as a parameter. sqlCommandQuery does not because it's called before the query is executed. Also, it's more complicated there because it supports multi-queries.
What is the driver and what is the table structure?
I don't know. There's also https://github.com/vrana/adminer/pull/420 which changes something Elasticsearch related.
I'd suggest to just use the plugin.