Update MIDI FS SysEx parsing logic and add unit tests for page incrementing

src/lib/midi/fsSysex.ts

@@ -136,9 +136,11 @@ export function buildSysExGetFileDataRequest(page: number) {
 }
 
 export function parseSysExGetFileDataResponse(bytes: Uint8Array) {
+  const page = (bytes[0] << 8) | bytes[1];
+
   return {
-    page: (bytes[0] << 8) | bytes[1],
-    nextPage: ((bytes[0] << 8) | (bytes[1] + 1)) & 0xffff,
+    page,
+    nextPage: (page + 1) & 0xffff,
     data: bytes.subarray(2),
   };
 }