stats: handle exceptions

[psychedelicious]

What type of PR is this? (check all applicable)

• Refactor
• Feature
• Bug Fix
• Optimization
• Documentation Update
• Community Node Submission

Description

fix(stats): fix fail case when previous graph is invalid

When retrieving a graph, it is parsed through pydantic. It is possible that this graph is invalid, and an error is thrown.

Handle this by deleting the failed graph from the stats if this occurs.

fix(stats): fix InvocationStatsService types

• move docstrings to ABC
• start_time: int -> start_time: float
• remove class attribute assignments in StatsContext
• add update_mem_stats() to ABC
• add class attributes to ABC, because they are referenced in instances of the class. if they should not be on the ABC, then maybe there needs to be some restructuring

QA Instructions, Screenshots, Recordings

On main (not this PR), create a situation in which an graph is valid but will be rendered invalid on invoke. Easy way in node editor:

• create an Integer Primitive node, set value to 3
• create a Resize Image node and add an image to it
• route the output of Integer Primitive to the width of Resize Image
• Invoke - this will cause first a Validation Error (expected), and if you inspect the error in the JS console, you'll see it is a "session retrieval error"
• Invoke again - this will also cause a Validation Error, but if you inspect the error you should see it originates in the stats module (this is the error this PR fixes)
• Fix the graph by setting the Integer Primitive to 512
• Invoke again - you get the same Validation Error originating from stats, even tho there are no issues

Switch to this PR, and then you should only ever get the Validation Error that that is classified as a "session retrieval error".

[psychedelicious]

I also fixed some typing issues in the stats module.

[lstein]

LGTM