message: Minor error message polishing.
diff: @@ -58,8 +58,8 @@ PrimitiveType GetUniqueOutputTypeOfFusion(const HloInstruction& instr) {
  for (size_t i = 1; i < outputs.size(); ++i) {
  PrimitiveType cur_output_type = outputs[i]->shape().element_type();
  CHECK(first_output_type == cur_output_type)
  - << "Output types are not unique, "
  - << PrimitiveType_Name(first_output_type) << " vs. "
  + << "Output types are expected to be unique, but see "
  + << PrimitiveType_Name(first_output_type) << " and "
  << PrimitiveType_Name(cur_output_type);
  }
  