Fix RTL plugin crash with empty formatted text sections

[Omkarthipparthi]

Description

Fixes crash when using RTL text plugin with formatted text-field expressions where all sections evaluate to empty strings.

Closes #6444

Problem

When using the RTL text plugin (@mapbox/mapbox-gl-rtl-text@0.3.0) with a formatted text-field where all sections are empty (e.g., both name and ref are null), the application crashes with:

Root Cause

The RTL plugin's processStyledBidirectionalText can return either:

• Tuples: [text, sectionIndex] (expected format)
• Objects: {text, sectionIndex} (some plugin versions/edge cases)

The shaping code in src/symbol/shaping.ts only handled tuples, causing taggedLine.text to be undefined when objects were returned, leading to crashes when later code accessed this.text.length.

Solution

Added defensive normalization logic (lines 331-361 in shaping.ts) to:

• Accept both tuple [text, sectionIndex] and object {text, sectionIndex} formats
• Provide safe fallbacks: empty string '' for text, empty array [] for sectionIndex
• Maintain backward compatibility with all RTL plugin versions

Testing

• All 17 integration shaping tests pass
• All 2476 unit tests pass (including 10 shaping-specific tests)
• Tested locally with @mapbox/mapbox-gl-rtl-text@0.3.0
• No regressions in existing functionality

Test Cases Verified

1. Empty formatted sections (the bug repro) - No crash
2. Arabic text with multiple sections - Renders correctly
3. Hebrew + English mixed RTL/LTR - Renders correctly
4. Partial empty sections (only name or ref) - Handles gracefully

Checklist

• Confirmed no backports from Mapbox projects
• Changes described above
• Linked to issue Undefined text property for formatted text with multiple empty sections and right to left plugin #6444
• No visual changes (bug fix only)
• All existing tests pass (17 integration + 2476 unit)
• No public API changes
• CHANGELOG.md updated

[HarelM]

Have we tried opening an issue to the RTL plugin repo?
I think it makes sense that the API will return the same type of object and that we won't need to patch it here if possible.

[Omkarthipparthi]

@HarelM
Yes, it makes sense to fix it in the RTL plugin to have a consistent return value type. Thanks for the heads up.
I have opened an issue and its respective PR.
mapbox/mapbox-gl-rtl-text#35
mapbox/mapbox-gl-rtl-text#36

[HarelM]

While this might have taken a little bit of time a new version will be released soon which will solve this issue, so I'm closing this PR.
If there are any issues do let me know.

[HarelM]

@Omkarthipparthi let me know if the latest version on main still has this issue. The plugin version was updated so main branch should not have this bug anymore.