"unsupported pattern in syntax match" at wrong spot

[Happyves]

Prerequisites

Please put an X between the brackets as you perform the following steps:

• [ X] Check that your issue is not already filed:
  https://github.com/leanprover/lean4/issues
• [X ] Reduce the issue to a minimal, self-contained, reproducible test case.
  Avoid dependencies to Mathlib or Batteries.
• [X ] Test your test case against the latest nightly release, for example on
  https://live.lean-lang.org/#project=lean-nightly
  (You can also use the settings there to switch to “Lean nightly”)

Description

MWE:

import Lean.Meta.Basic

open Lean Meta

def test1 : Nat := 
  let a : (Sum Nat Nat) := .inr 1
  let b : (Sum Nat Nat) := .inl 1
  let c : (Sum Nat Nat) := .inr 1
  match a, b, c with
  | .inr x , .inl y, inr z => return x+y+z
  | _,_,_ => return 37

def test2 : MetaM Nat:= do
  let a : MetaM (Sum Nat Nat) := return .inr 1
  let b : MetaM (Sum Nat Nat) := return .inl 1
  let c : MetaM (Sum Nat Nat) := return .inr 1
  match ← a, ← b, ← c with
  | .inr x , .inl y, inr z => return x+y+z
  | _,_,_ => return 37

def test3 : MetaM Nat:= do
  let a : MetaM (Sum Nat Nat) := return .inr 1
  let b : MetaM (Sum Nat Nat) := return .inl 1
  let c : MetaM (Sum Nat Nat) := return .inr 1
  let a ← a
  let b ← b
  let c ← c
  match a, b, c with
  | .inr x , .inl y, inr z => return x+y+z
  | _,_,_ => return 37

In test1, the correct error message invalid pattern, constructor ... is thrown, but in the two others, we get the incorrect unsupported pattern in syntax match .inr x

Context

No discussion on Zulip.

Steps to Reproduce

1. Copy mwe into live.lean

Expected behavior: Get test2 and test3 to display the same error as test1

Actual behavior: Incorrect error message

Versions

"4.21.0-nightly-2025-05-12"
live.lean-lang.org

Impact

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