Fix pyreverse crash on classes with EmptyNode instance attrs

[aryansk]

Description

Fixes #10767

pyreverse crashes with AttributeError: 'EmptyNode' object has no attribute 'name' when a class diagram includes a class whose instance_attrs contain synthetic EmptyNode entries. Astroid injects these placeholders when rebuilding certain classes — e.g. namedtuple results (the namedtuple brain sets attrname on EmptyNode nodes) and argparse.Namespace inference results.

The Linker.visit_classdef guarded against nodes.Unknown placeholders but not nodes.EmptyNode, so the placeholder was passed into the composition/aggregation/association relationship handlers, which dereferenced .name and crashed.

This change skips both placeholder types when extracting relationships.

Type of Changes

	Type
✓	🐛 Bug fix

Related Issue

Closes #10767

[HDPark95]

Reproduced the crash on main; this patch clears it.

Regression from #10397 (1abd975): at 1abd975c^, pyreverse -A -S over a namedtuple class emitted Point { x y } and the composition edge, here it emits Point { }. The brains set attrname, so handle_assignattr_type still works; only the new handler chain reads .name. Skipping just compositions_handler.handle restored the old output.

That turns tests/pyreverse 9 red, all from the new test leaving synthetic on a session-cached ClassDef. #8032 kept its crash regression in functional/class_diagrams/regression/.

[Pierre-Sassoulas]

Let's remove the unrelated changes in redfined-outer-name please.

[github-actions]

🤖 Effect of this PR on checked open source code: 🤖

Effect on sentry:

Removed messages:

Details

1. redefined-outer-name:
   Redefining name 'T' from outer scope (line 28)
   https://github.com/getsentry/sentry/blob/7a701584e61d8a093132eb37c45fd0359c1652ee/src/sentry/api/decorators.py#L31
2. redefined-outer-name:
   Redefining name 'P' from outer scope (line 28)
   https://github.com/getsentry/sentry/blob/7a701584e61d8a093132eb37c45fd0359c1652ee/src/sentry/api/decorators.py#L31
3. redefined-outer-name:
   Redefining name 'T' from outer scope (line 28)
   https://github.com/getsentry/sentry/blob/7a701584e61d8a093132eb37c45fd0359c1652ee/src/sentry/api/decorators.py#L45
4. redefined-outer-name:
   Redefining name 'P' from outer scope (line 28)
   https://github.com/getsentry/sentry/blob/7a701584e61d8a093132eb37c45fd0359c1652ee/src/sentry/api/decorators.py#L45
5. redefined-outer-name:
   Redefining name 'T' from outer scope (line 329)
   https://github.com/getsentry/sentry/blob/7a701584e61d8a093132eb37c45fd0359c1652ee/src/sentry/api/event_search.py#L332
6. redefined-outer-name:
   Redefining name 'T' from outer scope (line 329)
   https://github.com/getsentry/sentry/blob/7a701584e61d8a093132eb37c45fd0359c1652ee/src/sentry/api/event_search.py#L345
7. redefined-outer-name:
   Redefining name 'T' from outer scope (line 329)
   https://github.com/getsentry/sentry/blob/7a701584e61d8a093132eb37c45fd0359c1652ee/src/sentry/api/event_search.py#L354
8. redefined-outer-name:
   Redefining name 'T' from outer scope (line 34)
   https://github.com/getsentry/sentry/blob/7a701584e61d8a093132eb37c45fd0359c1652ee/src/sentry/workflow_engine/buffer/redis_hash_sorted_set_buffer.py#L425
9. redefined-outer-name:
   Redefining name 'T' from outer scope (line 34)
   https://github.com/getsentry/sentry/blob/7a701584e61d8a093132eb37c45fd0359c1652ee/src/sentry/workflow_engine/buffer/redis_hash_sorted_set_buffer.py#L431

This comment was generated for commit b4464f1

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 96.44%. Comparing base (5632ffe) to head (b4464f1).
⚠️ Report is 2 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #11278      +/-   ##
==========================================
+ Coverage   96.40%   96.44%   +0.04%     
==========================================
  Files         178      178              
  Lines       20020    20023       +3     
==========================================
+ Hits        19300    19311      +11     
+ Misses        720      712       -8     

Files with missing lines	Coverage Δ
pylint/checkers/variables.py	97.32% <100.00%> (+<0.01%)	⬆️
pylint/pyreverse/inspector.py	89.13% <100.00%> (+0.36%)	⬆️

... and 1 file with indirect coverage changes

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