See the discussion on #2174. An uncaught C++ error on main causes an error like:
```
TypeError: Cannot create property 'pyodide_fatal_error' on number '28811048'
```
With this the same error looks like:
```
Pyodide has suffered a fatal error. Please report this to the Pyodide maintainers.
The cause of the fatal error was:
CppException: Unable to cast Python instance to C++ type (compile in debug mode for details)
```
Support for C++ exceptions in packages. See the discussion on #2174. An uncaught C++ error on main causes an error like:
```
TypeError: Cannot create property 'pyodide_fatal_error' on number '28811048'
```
With this the same error looks like:
```
Pyodide has suffered a fatal error. Please report this to the Pyodide maintainers.
The cause of the fatal error was:
CppException: Unable to cast Python instance to C++ type (compile in debug mode for details)
```
package:
  name: attrs
  version: 21.4.0
source:
  sha256: 2d27e3784d7a565d36ab851fe94887c5eccd6a463168875832a1be79c82828b4
  url: https://files.pythonhosted.org/packages/be/be/7abce643bfdf8ca01c48afa2ddf8308c2308b0c3b239a44e57d020afa0ef/attrs-21.4.0-py2.py3-none-any.whl
requirements:
  run:
    - six
test:
  imports:
    - attr

package:
  name: attrs
  version: 21.4.0
source:
  sha256: 2d27e3784d7a565d36ab851fe94887c5eccd6a463168875832a1be79c82828b4
  url: https://files.pythonhosted.org/packages/be/be/7abce643bfdf8ca01c48afa2ddf8308c2308b0c3b239a44e57d020afa0ef/attrs-21.4.0-py2.py3-none-any.whl
requirements:
  run:
    - six
test:
  imports:
    - attr
