Either |- should not be inserted at all (and users will make sure {{row_template}} does it) or it is inserted after the header to separate the header and the first row. Fixed example:
{|
! header1
...
! headerN
|- <---- missing in the example
{{row_template
...
}}
|-
{{row_template
...
Example: https://cs.wikipedia.org/w/index.php?title=Wikipedista:Mat%C4%9Bj_Such%C3%A1nek/Seznam_jazyk%C5%AF_Wikipedie&oldid=20240363&action=edit
Either
|-
should not be inserted at all (and users will make sure{{row_template}}
does it) or it is inserted after the header to separate the header and the first row. Fixed example: