message: Fix MSVC warnings in quic (default branch)
  Summary: - add default branch to switch statement
diff: @@ -107,6 +107,8 @@ LongHeader* PacketHeader::asLong() {
  return &longHeader;
  case HeaderForm::Short:
  return nullptr;
  + default:
  + folly::assume_unreachable();
  }
  }
  @@ -116,6 +118,8 @@ ShortHeader* PacketHeader::asShort() {
  return nullptr;
  case HeaderForm::Short:
  return &shortHeader;
  + default:
  + folly::assume_unreachable();
  }
  }
  @@ -125,6 +129,8 @@ const LongHeader* PacketHeader::asLong() const {
  return &longHeader;
  case HeaderForm::Short:
  return nullptr;
  + default:
  + folly::assume_unreachable();
  }
  }
  @@ -134,6 +140,8 @@ const ShortHeader* PacketHeader::asShort() const {
  return nullptr;
  case HeaderForm::Short:
  return &shortHeader;
  + default:
  + folly::assume_unreachable();
  }
  }
  @@ -143,6 +151,8 @@ PacketNum PacketHeader::getPacketSequenceNum() const {
  return longHeader.getPacketSequenceNum();
  case HeaderForm::Short:
  return shortHeader.getPacketSequenceNum();
  + default:
  + folly::assume_unreachable();
  }
  }
  @@ -156,6 +166,8 @@ ProtectionType PacketHeader::getProtectionType() const {
  return longHeader.getProtectionType();
  case HeaderForm::Short:
  return shortHeader.getProtectionType();
  + default:
  + folly::assume_unreachable();
  }
  }
  @@ -165,6 +177,8 @@ PacketNumberSpace PacketHeader::getPacketNumberSpace() const {
  return longHeader.getPacketNumberSpace();
  case HeaderForm::Short:
  return shortHeader.getPacketNumberSpace();
  + default:
  + folly::assume_unreachable();
  }
  }
  