How query errors affect Postgresql DB performance
Does massive errors count affect the DB performance?


Not really. 

It will make the error log [a bit] larger, because each error gets written there, but that should be trivial in size compared to the database itself.  Each of those writes to the log will take [some] time, but not a great deal. 

What will get noticed is that the Application trying to execute these statements is failing to do so.
Each of those failures is losing company Data.
That matters. 

At some point, the Development team for the Application will get involved and they may well start throwing rocks in your direction because there's a table missing from the database.  Be prepared for the question: "Whose responsibility was it to create that table in the first place?"