reader: fix uninitialized variables when reading columns
reader: fix uninitialized variables when reading columns

mvertes/node-parquet,skale-me/node-parquet,skale-me/node-parquet,mvertes/node-parquet,mvertes/node-parquet,skale-me/node-parquet,mvertes/node-parquet,skale-me/node-parquet