[mlir] harden transform.test_emit_remark_and_erase (#136307)

Executing this transform op may crash when the payload op is not
erasable. Guard against that. Since this is a test op, no additional
test is defined.

Fixes #128323.

Author: ftynse

mlir/test/lib/Dialect/Transform/TestTransformDialectExtension.cpp

@@ -346,8 +346,11 @@ DiagnosedSilenceableFailure mlir::test::TestEmitRemarkAndEraseOperandOp::apply(
     transform::TransformRewriter &rewriter,
     transform::TransformResults &results, transform::TransformState &state) {
   emitRemark() << getRemark();
-  for (Operation *op : state.getPayloadOps(getTarget()))
+  for (Operation *op : state.getPayloadOps(getTarget())) {
+    if (!op->getUses().empty())
+      return emitSilenceableError() << "cannot erase an op that has uses";
     rewriter.eraseOp(op);
+  }
 
   if (getFailAfterErase())
     return emitSilenceableError() << "silenceable error";