Resolves: fdo#65823 crash on negative position in redlined word

there is possibly something deeper wrong here I think after all, see
946ea643 Resolves: fdo#84649 as well but for
now silence this and I can investigate further later

Change-Id: I1323584d1f71c14634d56ad4e4a705496b1bd1c0

sw/source/core/bastyp/breakit.cxx

@@ -108,7 +108,7 @@ sal_uInt16 SwBreakIt::GetRealScriptOfText( const OUString& rTxt, sal_Int32 nPos
 
         nScript = xBreak->getScriptType( rTxt, nPos );
         sal_Int32 nChgPos = 0;
-        if ( i18n::ScriptType::WEAK == nScript && nPos + 1 < rTxt.getLength() )
+        if (i18n::ScriptType::WEAK == nScript && nPos >= 0 && nPos + 1 < rTxt.getLength())
         {
             // A weak character followed by a mark may be meant to combine with
             // the mark, so prefer the following character's script