parser: minor cleanup in stmt() (#14136)

vlib/v/parser/parser.v

@@ -791,7 +791,7 @@ pub fn (mut p Parser) stmt(is_top_level bool) ast.Stmt {
 				spos := p.tok.pos()
 				name := p.check_name()
 				if name in p.label_names {
-					p.error_with_pos('duplicate label `$name`', spos)
+					return p.error_with_pos('duplicate label `$name`', spos)
 				}
 				p.label_names << name
 				p.next()
@@ -812,7 +812,7 @@ pub fn (mut p Parser) stmt(is_top_level bool) ast.Stmt {
 							return stmt
 						}
 						else {
-							p.error_with_pos('unknown kind of For statement', for_pos)
+							return p.error_with_pos('unknown kind of For statement', for_pos)
 						}
 					}
 				}