Linus Groh 1d728af5c4 LibWeb: Clear exceptions in each Document::run_javascript() call ...

We don't want to carry over exceptions across multiple
Document::run_javascript() calls as Interpreter::run() and every of its
exception checks will get confused - in this case there would be an
exception, but not because a certain action failed.

Real-life example:

<script>var a = {}; a.test()</script>
<script>alert("It worked!")</script>

The above HTML will invoke Document::run_javascript() twice, the first
call will result in a TypeError, which is still stored during the second
call. The interpreter will eventually call the following functions (in
order) for the alert() invocation:

- Identifier::execute()
- Interpreter::get_variable()
- Object::get() (on the global object)

That last Object::get() call has an exception check which is triggered
as we still carry around the exception from earlier - and eventually
returns an empty value.

Long story short, the second script will wrongly fail with
"ReferenceError, 'alert' is not defined".

Fixes #3091.

2020-08-11 21:08:30 +02:00

14 KiB

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