fix: allow optional abs_path and lineno for JsFrame

[samuelmaddock]

fixes #1580

It's possible for V8 to format a JS frame location to only contain <anonymous> (see AppendFileLocation). In such cases, JSON deserialization should pass, but symbolification should fail.

Here's an example call stack this addresses:

Error: Example unresponsive call stack
    at Object.hasOwnProperty (<anonymous>)

Also, this is the first Rust code I've written so please lmk what can be improved!

[codecov]

Codecov Report

Attention: Patch coverage is 62.50000% with 21 lines in your changes missing coverage. Please review.

Project coverage is 73.57%. Comparing base (5a85fd7) to head (b381fe3).
Report is 201 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #1581      +/-   ##
==========================================
- Coverage   76.09%   73.57%   -2.52%     
==========================================
  Files         101      105       +4     
  Lines       15262    15903     +641     
==========================================
+ Hits        11613    11700      +87     
- Misses       3649     4203     +554     

[Dav1dde]

Just left some small Rust nits, otherwise looks good to me, but I want to wait on @loewenheim for a review, since I can't really judge the implications of the change fully.

Also would be great if you can add a test, I think symbolicator-js/tests/integration/sourcemap.rs should be the right place and pretty low effort to add.

[Dav1dde]

Can use abs_path.to_owned() here now, I think, since we already checked for Some before.

Suggested change

	.unwrap_or_else(|| raw_frame.abs_path.clone().unwrap_or_default());
	.unwrap_or_else(|| abs_path.to_owned());

[samuelmaddock]

I had to revert this in 12d1d5e to fix a compilation error

error[E0502]: cannot borrow `*raw_frame` as mutable because it is also borrowed as immutable
   --> crates/symbolicator-js/src/symbolication.rs:145:17
    |
105 |   ...ath = raw_frame
    |  __________-
106 | | ...path
    | |_______- immutable borrow occurs here
...
145 |   ...   apply_source_context(raw_frame, minified_source.contents(...
    |         ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ mutable borrow occurs here
...
163 |   ...ap_or_else(|| abs_path.to_owned());
    |                    -------- immutable borrow later captured here by closure

[samuelmaddock]

@Dav1dde I've added a couple snapshot tests in 41144b1