If I issue a %gui tk (no need to actually run any code that uses tk), then after a second or so, executing a cell gets stuck in the [*] state, this is recoverable by interrupting and running the cell again. From that point on, cells can be run normally, but if running a cell causes a python traceback to occur, then the next attempt at executing a cell results in the  state, and the only way to get out of it is to restart the kernel. Simplest steps to reproduce:
- %gui tk
- 0/0 # May get stuck in [*] state, interrupt and run again
- 1+1 # The notebook will hang at this point, requiring a kernel restart
Should I open an issue?
Python 3.8.8, jupyter 1.0.0, jupyter_server 1.4.1. What other package versions should I provide?