fix(importer): skip GPIF tempo automations on missing master bars

[kaizenman]

Issues

Fixes #2675

Proposed changes

GpifParser._buildModel iterates _masterTrackAutomations and dereferences score.masterBars[barNumber] without checking that the index is in range:

const masterBar: MasterBar = this.score.masterBars[barNumber];
// masterBar can be undefined when barNumber >= masterBars.length

On real-world Guitar Pro 7/8 files where the score has been edited (e.g. bars removed) without removing the corresponding <MasterTrack> automations, or in files with off-by-one bar indices, this throws:

TypeError: Cannot read properties of undefined (reading 'tempoAutomations')
    at GpifParser._buildModel (GpifParser.ts:2900)
    at GpifParser.parseXml (GpifParser.ts:176)
    at Gp7To8Importer.readScore (Gp7To8Importer.ts:75)

Reproducer

test-data/guitarpro8/orphan-tempo-automation.gp — a published Guitar Pro 8 file with 100 master bars and tempo automations targeting bars [0, 91-95, 97-100]. The automation at bar 100 is one past the score's last bar (off-by-one).

Fix

Skip the automation if the master bar is absent — matches Guitar Pro desktop behavior (silently ignores orphan automations and renders the score normally):

const masterBar: MasterBar | undefined = this.score.masterBars[barNumber];
if (!masterBar) {
    // automation references a bar that is not in the score's masterBars list
    continue;
}

Tests

Gp8ImporterTest > orphan-tempo-automation — loads the fixture and asserts masterBars.length === 100, tracks.length === 3. Without the fix this test throws the TypeError above.

All 27 GP8 importer tests pass.

Note

One of three independent fixes in the same area. The others address distinct root causes:

• fix(importer): cap chord name read at field width in GP3-5 binary parser #2669 — GP3-5 chord name overflow misalignment
• fix(importer): bound runaway loops on corrupt count fields in GP3-5 binary parser #2670 — GP3-5 unbounded count field DoS

Checklist

• I consent that this change becomes part of alphaTab under it's current or any future open source license
• Changes are implemented
• New tests were added

Further details

• This is a breaking change
• This change will require update of the documentation/website

[Danielku15]

Thanks for the fixes, can you open counterpart bug reports following the template so we have proper tracking of these items? Also: the issue and PR templates are not optional, please be sure to update your description accordingly.

[Danielku15]

Thanks for the fixes, can you open counterpart bug reports following the template so we have proper tracking of these items? Also: the issue and PR templates are not optional, please be sure to update your description accordingly.

[kaizenman]

Thanks for the pointer. I've opened bug reports — #2671, #2672, #2673 (one per PR) plus #2674 to track the follow-up scope from PR #2670 — and updated all three PR descriptions to follow the template.

[Danielku15]

This is not C# and Kotlin transpilation compatible. Add a custom out-of-bounds check instead of relying on undefined returns.