Current state

Today we just bomb out and log errors in cell output (session cannot be created)
Error message is very confusing to the user (no indication that kernel is dead)
- Users are used to seeing errors from kernels in output (not extension), hence they might be under the impression these are errors from kernel & attempt to re-execute cells
User needs to manually restart the kernel

Proposed Solution

Notify user when kernel dies (like jupyter)
Allow user to restart kernel (like jupyter)
Include error message from kernel (so users know what went wrong)
- E.g. if kernel fails due to some package, or the like, then they know what caused it
- Else all they know is kernel died and could end up just blaming vscode extension
- I.e. we need to provide the user with tools necessary to resolve the issue themselves
If we were able to successfully run a cell (or start the kernel), then ask user to inspect the particular cell that caused the issue
- E.g. we've found kernels crash when users have busted packages
- This way users will know what to look at and diagnose the issue.
- Plenty of examples
- Error: Direct kernel connection broken #1706
- Kernel crashes when importing tensorflow #7600
- Bad conda environment causes a notebook to not be able to be opened #4855
Warn users when files override built in packages that could have caused the kernel to fail #7538
Prompt the user to restart the kernel when running a cell against a dead kernel #7399
Kernel issues with Python 2.7 #4680
Display warning when user selects outdated versions of Python #7960
Recommend renaming python file if python file it overwrites builtins #8195