Deleting cell content raises exception

[richardlin047]

If I delete the content of a cell of a CSV I've uploaded, the following exception is raised error:org.springframework.messaging.handler.invocation.AbstractMethodMessageHandler processHandlerMethodException. Adding new cells and updating the value to a non-empty value does not error.

The following csv was used:

a, 1
b, 2
c, 3

The following system setup was used: (According to https://github.com/dataspread/dataspread-web/wiki/Setting-up-Developer-Environment)
PostgreSQL - 9.5
Deployment on IntelliJ local Tomcat server (9.0.31)
PostgreSQL JDBC driver - 9.4.1208

[twattanawaroon]

This looks like #177 manifesting differently. I don't think we've really implemented "delete", afaik.