fix(tracker): loading preset did not update the ids

When a preset was loaded, its IDs were not updated,
causing ID collisions in the song and send targets
going wrong.

CHANGELOG.md

@@ -29,6 +29,8 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
   x87 stack.
 
 ### Fixed
+- Loading a preset did not update the IDs of the newly loaded instrument,
+  causing ID collisions and sends target wrong units.
 - The x87 native filter unit was denormalizing and eating up a lot of CPU ([#68][i68])
 - Modulating delaytime in wasm could crash, because delay time was converted to
   int with i32.trunc_f32_u. Using i32.trunc_f32_s fixed this.

tracker/presets.go

@@ -145,7 +145,9 @@ func (m *Model) LoadPreset(index int) Action {
 		for m.d.InstrIndex >= len(m.d.Song.Patch) {
 			m.d.Song.Patch = append(m.d.Song.Patch, defaultInstrument.Copy())
 		}
-		m.d.Song.Patch[m.d.InstrIndex] = instrumentPresets[index].Copy()
+		newInstr := instrumentPresets[index].Copy()
+		(*Model)(m).assignUnitIDs(newInstr.Units)
+		m.d.Song.Patch[m.d.InstrIndex] = newInstr
 	}, allowed: func() bool {
 		return true
 	}}