As is true for most special methods, it is a bug for __repr__ methods to raise.  They should return a string, as documented.

Special method wrappers generally assume that the wrapped methods work.  In particular, repr assumes this, and so do the __repr__ methods of all collections classes.  They do not try to hide bugs.  Example:

>>> class BadRep:
	def __repr__(self): 1/0

	
>>> br = BadRep()
>>> [br]
Traceback (most recent call last):
  File "<pyshell#8>", line 1, in <module>
    [br]
  File "C:\Programs\Python39\lib\idlelib\rpc.py", line 620, in displayhook
    text = repr(value)
  File "<pyshell#6>", line 2, in __repr__
    def __repr__(self): 1/0
ZeroDivisionError: division by zero

Bugs should be reported, not masked.  I don't think that FrameSummary should be an exception to this.  Therefore I think that this issue should be closed (along with the PR) as 'not a bug'.