Topology and configuration file missmatch handling

[ErikPoppleton]

If the .dat and .top files are missmatched, the correct error is thrown, but the page must be refreshed before files can be dropped again. This should clear the variables and prepare the canvas for another drop.

[lorenzo-rovigatti]

I think that's not always true. If you have a pathologically wrong topology file (right number of nucleotides at the top but wrong number of lines), the viewer spits out a hard-to-parse error. I attach a very simple example where I removed a line from the topology file of a simple hairpin.

To reproduce it, just go to oxDNA/examples/HAIRPIN, remove a line from initial.top and try to visualise it. Note that I work with a lot of exporters/converters and it is pretty common to work with "wrong" topology files. In fact, I found this bug while debugging the vHelix converter on http://tacoxdna.sissa.it/.

[ErikPoppleton]

Thanks, I'll look into it and see if I can come up with a better error. That one you're getting is because the particle that you deleted from the topology is referenced as a neighbor by another particle, so when it tries to draw the backbone, it hits a nucleotide that is referenced as a neighbor, but itself has neither neighbors nor is a strand end and that breaks the backbone position calculation.

[lorenzo-rovigatti]

I think the better course would be to flat out fail loading the configuration if there is a mismatch between the number of nucleotides as specified in the first line and the number of lines (+1) that the topology file contains