[fix] Fix a crash when the root of a node is not a module but is unknown

[Pierre-Sassoulas]

Type of Changes

	Type
✓	🐛 Bug fix

Description

Closes #2672

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 93.25%. Comparing base (59f36e7) to head (881402f).
Report is 2 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2739      +/-   ##
==========================================
+ Coverage   93.21%   93.25%   +0.03%     
==========================================
  Files          93       93              
  Lines       11072    11072              
==========================================
+ Hits        10321    10325       +4     
+ Misses        751      747       -4     

Flag	Coverage Δ
linux	93.11% <100.00%> (+0.03%)	⬆️
pypy	93.25% <100.00%> (+0.03%)	⬆️
windows	93.23% <100.00%> (+0.03%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
astroid/nodes/node_ng.py	92.63% <100.00%> (ø)

... and 2 files with indirect coverage changes

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[github-actions]

The backport to maintenance/3.3.x failed:

The process '/usr/bin/git' failed with exit code 1

To backport manually, run these commands in your terminal:

# Fetch latest updates from GitHub
git fetch
# Create a new working tree
git worktree add .worktrees/backport-maintenance/3.3.x maintenance/3.3.x
# Navigate to the new working tree
cd .worktrees/backport-maintenance/3.3.x
# Create a new branch
git switch --create backport-2739-to-maintenance/3.3.x
# Cherry-pick the merged commit of this pull request and resolve the conflicts
git cherry-pick -x --mainline 1 97aac5237d4dac1a6ebef606df75f92c630a3d33
# Push it to GitHub
git push --set-upstream origin backport-2739-to-maintenance/3.3.x
# Go back to the original working tree
cd ../..
# Delete the working tree
git worktree remove .worktrees/backport-maintenance/3.3.x

Then, create a pull request where the base branch is maintenance/3.3.x and the compare/head branch is backport-2739-to-maintenance/3.3.x.

[Pierre-Sassoulas]

Backporting this create a new crash, beside the maintenance branch does not need this fix because it was introduced in the main branch only in #2536. Reopened #120 because it wasn't fixed.