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: bleach
  version: 4.1.0
requirements:
  run:
    - webencodings
    - packaging
    - six
source:
  sha256: 4d2651ab93271d1129ac9cbc679f524565cc8a1b791909c4a51eac4446a15994
  url: https://files.pythonhosted.org/packages/64/cc/74d634e1e5659742973a23bb441404c53a7bedb6cd3962109ca5efb703e8/bleach-4.1.0-py2.py3-none-any.whl
test:
  imports:
    - bleach

package:
  name: bleach
  version: 4.1.0
requirements:
  run:
    - webencodings
    - packaging
    - six
source:
  sha256: 4d2651ab93271d1129ac9cbc679f524565cc8a1b791909c4a51eac4446a15994
  url: https://files.pythonhosted.org/packages/64/cc/74d634e1e5659742973a23bb441404c53a7bedb6cd3962109ca5efb703e8/bleach-4.1.0-py2.py3-none-any.whl
test:
  imports:
    - bleach
