fix(core) Include causes when converting anyhow errors to JS exceptions (#16397)

When an op returns an `anyhow` error with a cause (usually added using
the `.context()` method), the `Error` thrown into JavaScript contains
only the message of the outernmost error in the chain.

This PR simply changes the formatting of `anyhow::Error` from `"{}"` to
`"{:#}"`:

This significantly improves errors for code that embeds Deno and defines
custom ops. For example, in
[chiselstrike/chiselstrike](https://github.com/chiselstrike/chiselstrike),
this PR improves an error message like

```
Error: could not plan migration
```

to

```
Error: could not plan migration: could not migrate table for entity "E": could not add column for field "title": the field does not have a default value
```

1 files changed, 1 insertions, 1 deletions

diff --git a/core/ops.rs b/core/ops.rs
index b339b7d01..8694324ad 100644
--- a/core/ops.rs
+++ b/core/ops.rs
@@ -133,7 +133,7 @@ impl OpError {
   pub fn new(get_class: GetErrorClassFn, err: Error) -> Self {
     Self {
       class_name: (get_class)(&err),
-      message: err.to_string(),
+      message: format!("{:#}", err),
       code: crate::error_codes::get_error_code(&err),
     }
   }