KeyError: ReservedString(})

I've tried to apply mutmut to PyPDF2 and failed. Initially I thought the issue was with mutmut ( https://github.com/boxed/mutmut/issues/252 ) , but I guess it's a parso bug.

## Minimal example

```python
import parso

parso.parse('stream.write(b_(rf"\{ord_(c):0>3o}"))', error_recovery=False)
```

## Traceback

```
Traceback (most recent call last):
File "/home/moose/.pyenv/versions/3.10.2/lib/python3.10/site-packages/parso/parser.py", line 180, in _add_token
plan = stack[-1].dfa.transitions[transition]
KeyError: ReservedString(})

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
File "", line 1, in
File "/home/moose/.pyenv/versions/3.10.2/lib/python3.10/site-packages/parso/__init__.py", line 58, in parse
return grammar.parse(code, **kwargs)
File "/home/moose/.pyenv/versions/3.10.2/lib/python3.10/site-packages/parso/grammar.py", line 156, in parse
root_node = p.parse(tokens=tokens)
File "/home/moose/.pyenv/versions/3.10.2/lib/python3.10/site-packages/parso/python/parser.py", line 79, in parse
return super().parse(tokens)
File "/home/moose/.pyenv/versions/3.10.2/lib/python3.10/site-packages/parso/parser.py", line 129, in parse
self._add_token(token)
File "/home/moose/.pyenv/versions/3.10.2/lib/python3.10/site-packages/parso/parser.py", line 186, in _add_token
self.error_recovery(token)
File "/home/moose/.pyenv/versions/3.10.2/lib/python3.10/site-packages/parso/python/parser.py", line 140, in error_recovery
return super().error_recovery(token)
File "/home/moose/.pyenv/versions/3.10.2/lib/python3.10/site-packages/parso/parser.py", line 152, in error_recovery
raise ParserSyntaxError('SyntaxError: invalid syntax', error_leaf)
parso.parser.ParserSyntaxError: ('SyntaxError: invalid syntax', )
```

## Environment

```
$ python --version
Python 3.10.2

>>> parso.__version__
'0.8.3'
```