PVS-Studio warning V522 for Clang

void MatcherGen::EmitLeafMatchCode(const TreePatternNode *N) {
  ...
  if (DI == 0) {
    errs() << "Unknown leaf kind: " << *DI << "\n";
    abort();
  }
  ...
}

This suspicious code was found in Clang project by PVS-Studio static code analyzer.
Warning message is:
V522 Dereferencing of the null pointer 'DI' might take place. llvm-tblgen dagiselmatchergen.cpp 220

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