grdblen crashes with externals when input grids must be resampled.

[joa-quim]

See topic in forum

The problem arises when grdsample is called and the output tries to overwrite an external object
https://github.com/GenericMappingTools/gmt/blob/master/src/grdblend.c#L474

B[n].G->data then points to invalid memory and a crash follows later when trying to access it.

[PaulWessel]

That grdsample command writes to a temporary file called grdblend_resampled_?_?.grd, so I dont think related to writing. Perhaps grdblend is trying to do something to the external input grid related to pads?

[PaulWessel]

I should have some time this afternoon to try out the Julia debug instructions etc.

[joa-quim]

Debugging from Julia calls is becoming impossibly slow. Probably I meant what happens in
https://github.com/GenericMappingTools/gmt/blob/master/src/grdblend.c#L501