Make this a release assert, since otherwise parse errors crash NDEBUG builds in weird ways

src/codegen/parser.cpp

@@ -67,7 +67,7 @@ public:
 
     uint8_t readByte() {
         ensure(1);
-        assert(end > start && "premature eof");
+        RELEASE_ASSERT(end > start, "premature eof");
         if (VERBOSITY("parsing") >= 2)
             printf("readByte, now %d %d\n", start + 1, end);
         return buf[start++];