Segfault when using integral(proc), if proc not yet integrated

[kilian]

This happens here, for instance:

process proc = e1, E1 => e1, E1
plot cross_section (0, 2 TeV)
scan sqrts = (1 TeV) { record cross_section (sqrts, integral(proc)) }

if there was no integration for proc.

There is an error message, but the segfault should be caught nevertheless.

[Juergen Reuter]

Strangely, on 32bit Linux I cannot reproduce, on the MAC (on which it is always awfully stressful to generate core files) the seg fault occurs. So, please go ahead with this! :-(

[Christian Speckner]

Fixed by making this fatal in r2318. This is a design flaw in the parser and "compiler": in case of an error, evaluation nodes and parse nodes are in an undefined state (note even nullified), leading to potentially hard to track down segfaults further downstream. This should be caught by proper error handling -> creating a new enhancement ticket and closing this one.