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

GpifParser._buildModel iterated _masterTrackAutomations and dereferenced
score.masterBars[barNumber] without checking that the index was within
range. Real-world GP7/8 files (off-by-one indexing, scores edited to
fewer bars) reference bar numbers past the masterBars list, producing:

  TypeError: Cannot read properties of undefined (reading 'tempoAutomations')

Skip the automation if the master bar is absent. The fixture
test-data/guitarpro8/orphan-tempo-automation.gp has 100 master bars and
a tempo automation targeting bar 100 (off-by-one) that previously
crashed the importer.

Author: kaizenman

packages/alphatab/src/importer/GpifParser.ts

@@ -2892,7 +2892,11 @@ export class GpifParser {
 
         // build masterbar automations
         for (const [barNumber, automations] of this._masterTrackAutomations) {
-            const masterBar: MasterBar = this.score.masterBars[barNumber];
+            const masterBar: MasterBar | undefined = this.score.masterBars[barNumber];
+            if (!masterBar) {
+                // automation references a bar that is not in the score's masterBars list
+                continue;
+            }
             for (let i: number = 0, j: number = automations.length; i < j; i++) {
                 const automation: Automation = automations[i];
                 switch (automation.type) {

packages/alphatab/test-data/guitarpro8/orphan-tempo-automation.gp

@@ -510,4 +510,14 @@ describe('Gp8ImporterTest', () => {
         const score = reader.readScore();
         GpImporterTestHelper.checkHarmonics(score);
     });
+
+    it('orphan-tempo-automation', async () => {
+        // GPIF tempo automations can reference bar indices that are not
+        // present in the score's masterBars list (e.g. off-by-one or after
+        // bar deletion). Should be skipped instead of null-dereferencing.
+        const reader = await prepareImporterWithFile('guitarpro8/orphan-tempo-automation.gp');
+        const score = reader.readScore();
+        expect(score.masterBars.length).to.equal(100);
+        expect(score.tracks.length).to.equal(3);
+    });
 });