Error Handling

Hardwood throws specific exceptions for common error conditions:

Exception	When
IOException	Any I/O error: invalid Parquet file (bad magic number, corrupt footer), local-disk read errors, S3 transport failures (after retry exhaustion — see Read from S3)
UnsupportedOperationException	Compression codec library not on classpath — the message names the required dependency
IllegalArgumentException	Accessing a column not in the projection, or invalid column name
NullPointerException	Calling a primitive accessor (getInt, getLong, etc.) on a null field without checking isNull() first
NoSuchElementException	Calling next() on a RowReader when hasNext() returns false
IllegalStateException	Calling ColumnReader accessors before nextBatch(), or calling nested-column methods on a flat column