Error with Reader Node

Hi all,
When using knime (i coded a geo-spatiale data node reader), i 've got this error

Buffer CODING PROBLEM Writing cells to temporary buffer must not throw NullPointerException

Does anyone know how does it mean this error code?


Are you using custom data types (have you written your own type?) Can you send the stack trace from the log file (location printed in one of the first lines in the console view, usually <runtime-workspace>/.metadata/knime/knime.log)

Thank you wiswedel,
I’ve solved problem i was facing. it had been caused by a null geometry data manipulation.
So, to answer to y’re question, i’m using custom data type specially geometry data type so to make Knime capable to mine geospatial data.