[python] handle storage Sync issues properly

[agners]

The variable "path" doesn't exist when handling this exception. Use
self._file and return after reporting the error to avoid further
exceptions.

Problem

What is being fixed? Examples:

• Fix crash on startup

2022-04-30 11:00:22 allenwind root[270500] CRITICAL Loading configuration from /tmp/chip-device-ctrl-storage.json...                                                                                                                                                                                                                                                                                                          
2022-04-30 11:00:22 allenwind root[270500] INFO SetSdkKey: g/gcc = b'\xd0\x07\x00\x00'                                                                                                                                                                                                                                                                                                                                        
Exception ignored on calling ctypes callback function: <function _OnSyncSetKeyValueCb at 0x7f6230043af0>                                                                                                                                                                                                                                                                                                                      
Traceback (most recent call last):                                                                                                                                                                                                                                                                                                                                                                                            
  File "/home/sag/projects/project-chip/connectedhomeip/out/python_env/lib/python3.9/site-packages/chip/storage/__init__.py", line 44, in _OnSyncSetKeyValueCb                                                                                                                                                                                                                                                                
    storageObj.SetSdkKey(key.decode("utf-8"), ctypes.string_at(value, size))                                                                                                                                                                                                                                                                                                                                                  
  File "/home/sag/projects/project-chip/connectedhomeip/out/python_env/lib/python3.9/site-packages/chip/storage/__init__.py", line 147, in SetSdkKey                                                                                                                                                                                                                                                                          
    self.Sync()                                                                                                                                                                                                                                                                                                                                                                                                               
  File "/home/sag/projects/project-chip/connectedhomeip/out/python_env/lib/python3.9/site-packages/chip/storage/__init__.py", line 111, in Sync                                                                                                                                                                                                                                                                               
    f"Could not open {path} for writing configuration. Error:")                                                                                                                                                                                                                                                                                                                                                               
NameError: name 'path' is not defined

Change overview

Improve exception handling.

Testing

How was this tested? (at least one bullet point required)

• If unit tests were added, how do they cover this issue?
• If unit tests existed, how were they fixed/modified to prevent this in future?
• If new unit tests are not added, why not?
• If integration tests were added, how do they verify this change?
• If new integration tests are not added, why not?
• If manually tested, what platforms controller and device platforms were manually tested, and how?
• If no testing is required, why not?

[stale]

This pull request has been automatically marked as stale because it has not had recent activity. It will be closed if no further activity occurs.

[agners]

Ping, I think this should be ready to be merged.