I wonder if adding columns is not supported - because some tools
would define the table without the extra column? You might have
to define a new data table instead (with largely the same content).
But to be clear, I am not an expert in this area of Galaxy.
However, it does seem the IUC could lay out some *.loc file best
practises for tool authors. There is currently a TODO entry here:
On Mon, Sep 17, 2018 at 10:56 PM Peter van Heusden <email@example.com
A bit more tracing leads me to suspect that what is happening is that a merge is being called here:
i.e. the toolshed maintains an in-memory copy of tool-data tables and if the list of columns in an incoming tool-data table is not the same as the in-memory version the error I saw happens.
Which leaves me with the question: how is one meant to update the column list of a tool data table?