Narrow message_handler's parameter to notifications and exceptions #3642

Job	Run time
checks / pre-commit	55s
checks / test (3.12, locked, windows-latest)	2m 0s
checks / test (3.11, lowest-direct, ubuntu-latest)	1m 22s
checks / readme-snippets	15s
checks / test (3.12, locked, ubuntu-latest)	1m 29s
checks / docs	1m 3s
checks / test (3.12, lowest-direct, windows-latest)	1m 56s
checks / test (3.13, locked, windows-latest)	1m 56s
checks / test (3.14, lowest-direct, windows-latest)	2m 1s
checks / test (3.11, locked, ubuntu-latest)	1m 25s
checks / test (3.10, locked, ubuntu-latest)	1m 31s
checks / test (3.13, lowest-direct, ubuntu-latest)	1m 25s
checks / test (3.14, locked, ubuntu-latest)	1m 18s
checks / test (3.11, locked, windows-latest)	1m 35s
checks / test (3.10, locked, windows-latest)	2m 9s
checks / test (3.10, lowest-direct, windows-latest)	2m 0s
checks / test (3.11, lowest-direct, windows-latest)	2m 12s
checks / test (3.10, lowest-direct, ubuntu-latest)	1m 9s
checks / test (3.13, locked, ubuntu-latest)	1m 14s
checks / test (3.12, lowest-direct, ubuntu-latest)	1m 31s
checks / test (3.14, locked, windows-latest)	1m 54s
checks / test (3.14, lowest-direct, ubuntu-latest)	1m 8s
checks / test (3.13, lowest-direct, windows-latest)	2m 1s
all-green	5s
	35m 34s

Provide feedback