Avoiding referencing elements of an empty vector

src/hash.cpp

@@ -9,6 +9,8 @@ unsigned int MurmurHash3(unsigned int nHashSeed, const std::vector<unsigned char
 {
     // The following is MurmurHash3 (x86_32), see http://code.google.com/p/smhasher/source/browse/trunk/MurmurHash3.cpp
     uint32_t h1 = nHashSeed;
+    if (vDataToHash.size() > 0)
+    {
         const uint32_t c1 = 0xcc9e2d51;
         const uint32_t c2 = 0x1b873593;
 
@@ -48,6 +50,7 @@ unsigned int MurmurHash3(unsigned int nHashSeed, const std::vector<unsigned char
             k1 *= c2;
             h1 ^= k1;
         };
+    }
 
     //----------
     // finalization