quic: address coverity warning

- initiaze variable in similar way down in other
  constructors

Signed-off-by: Michael Dawson <midawson@redhat.com>
PR-URL: #52824
Reviewed-By: Yagiz Nizipli <yagiz.nizipli@sentry.io>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Tobias Nießen <tniessen@tnie.de>

src/quic/data.cc

@@ -169,6 +169,7 @@ QuicError::QuicError(const std::string& reason)
 
 QuicError::QuicError(const ngtcp2_ccerr* ptr)
     : reason_(reinterpret_cast<const char*>(ptr->reason), ptr->reasonlen),
+      error_(),
       ptr_(ptr) {}
 
 QuicError::QuicError(const ngtcp2_ccerr& error)