[FIX] owhierarchicalclustering: Fix IndexError

[ales-erjavec]

Issue

File -> Table -> Distances -> Hierarchical Clustering

Select some rows in Table, color by some variable in Hierarchical Clustering now extend the selection in Table (cmd + click) with new instances (must output more data then before).

Raises

---------------------------- IndexError Exception -----------------------------
Traceback (most recent call last):
  File "/home/ales/devel/orange3/Orange/widgets/unsupervised/owhierarchicalclustering.py", line 152, in data
    return self.__colors[index.row()]
           ~~~~~~~~~~~~~^^^^^^^^^^^^^
IndexError: index 12 is out of bounds for axis 0 with size 12
-------------------------------------------------------------------------------

and then it segfaults.

Description of changes

Fix IndexError

Includes

• Code changes
• Tests
• Documentation

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 88.47%. Comparing base (876acb2) to head (bb1c1c7).
Report is 3 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #6989   +/-   ##
=======================================
  Coverage   88.47%   88.47%           
=======================================
  Files         332      332           
  Lines       73294    73296    +2     
=======================================
+ Hits        64847    64852    +5     
+ Misses       8447     8444    -3