Button with Default is true ( Is it a bug?)

I create a popup like the picture. 

webblock1 is displayed when some condition is ok.

I use ajax refresh to refresh webblock1.

I find when i press entery key in [Input] box , I got javascript error like this :

 Uncaught SyntaxError: Unexpected token 'return'

I inspect the Input , i find the javascript code is generated by outsystems.
Is it a bug ? why two [return] is in the code?

onkeydown="return OsEnterKey('BaseTheme_wt2_block_wtMainContent_wt1_wt26_wtSearchButton', arguments[0] || window.event)return OsEnterKey('BaseTheme_wt2_block_wtMainContent_wt1_wt26_wtSearchButton', arguments[0] || window.event)"

Thank you , very much

Mmm, I vaguely recall having seen this before, but I don't remember what the solution was, if any...