fix ZIR decoding of error notes

src/AstGen.zig

@@ -10382,7 +10382,7 @@ fn appendErrorTok(
     comptime format: []const u8,
     args: anytype,
 ) !void {
-    try astgen.appendErrorTokNotes(token, format, args, &[0]u32{});
+    try astgen.appendErrorTokNotesOff(token, 0, format, args, &[0]u32{});
 }
 
 fn failTokNotes(
@@ -10392,7 +10392,7 @@ fn failTokNotes(
     args: anytype,
     notes: []const u32,
 ) InnerError {
-    try appendErrorTokNotes(astgen, token, format, args, notes);
+    try appendErrorTokNotesOff(astgen, token, 0, format, args, notes);
     return error.AnalysisFail;
 }
 

src/Compilation.zig

@@ -2909,7 +2909,7 @@ pub fn addZirErrorMessages(eb: *ErrorBundle.Wip, file: *Module.File) !void {
                     .column = @intCast(u32, err_loc.column),
                     .source_line = try eb.addString(err_loc.source_line),
                 }),
-                .notes_len = item.data.notes,
+                .notes_len = item.data.notesLen(file.zir),
             });
         }
 

src/Zir.zig

@@ -3594,6 +3594,12 @@ pub const Inst = struct {
             /// 0 or a payload index of a `Block`, each is a payload
             /// index of another `Item`.
             notes: u32,
+
+            pub fn notesLen(item: Item, zir: Zir) u32 {
+                if (item.notes == 0) return 0;
+                const block = zir.extraData(Block, item.notes);
+                return block.data.body_len;
+            }
         };
     };