Fix aref_field bracket consumption causing invalid source_range

[dduugg]

Description

Fixes #1420

I caused the above regression four years ago and am proposing a fix here. This PR was heavily AI-assisted.

The issue occurred when parsing code with an aref assignment (a[:b] = 1) followed by a constant assignment using aref (X = a[:b]). The parser would create an invalid source_range for the constant's aref node, where the ending position was less than the beginning position.

Root Cause:

When Ripper encounters an aref on the left-hand side of an assignment (e.g., a[:b] = 1), it calls on_aref_field instead of on_aref. The on_aref_field method was not consuming the closing bracket position from @map[:aref], which tracks bracket positions. This left the bracket position from the assignment in the map.

When the next aref expression (X = a[:b]) was parsed, on_aref would shift the old bracket position from @map[:aref], causing it to use the wrong ending position and create an invalid source_range where end < begin.

The Fix:

Updated on_aref_field to match the behavior of on_aref:

• Consume the closing bracket position from @map[:aref] using shift
• Use the bracket position to correctly calculate the source_range
• Set both source_range and line_range based on the actual bracket position

This ensures that when on_aref_field processes a[:b] = 1, it consumes the bracket, so when on_aref processes X = a[:b], it gets the correct bracket position and creates a valid source_range.

Changes:

• Modified on_aref_field in lib/yard/parser/ruby/ruby_parser.rb to consume bracket positions from @map[:aref] and calculate source_range correctly
• Added spec to verify constant assignments with aref after aref assignments parse correctly with valid source_range

The fix ensures both on_aref and on_aref_field handle bracket consumption consistently, preventing the parser from getting confused by previous aref assignments.

Completed Tasks

• I have read the Contributing Guide.
• The pull request is complete (implemented / written).
• Git commits have been cleaned up (squash WIP / revert commits).
• I wrote tests and ran bundle exec rake locally (if code is attached to PR).

[lsegal]

Thank you!