Bad error message for full SubSmallExtension

[jodavies]

If you fill the SubSmallExtension:

* Sort which fills (sub)smallextension:

#: SmallSize 1000K
#: SmallExtension 1200K
#: TermsInSmall 2M
#: SubSmallSize 1000K
#: SubSmallExtension 1200K
#: SubTermsInSmall 2M

Symbol x,n;
CFunction f,g,prf;
CFunction hold;

Local test = 1;
.sort

PolyRatFun prf;
Term;
   Multiply (<f(1)>+...+<f(150)>)*(<g(1)>+...+<g(100)>);
   Identify f(x?) = prf(n-x,n+x);
EndTerm;

.end

FORM crashes with Please increase SmallExtension in form.set. Of course, increasing SmallExtension will never get you anywhere in this case.

I've not yet worked out how to determine here
https://github.com/vermaseren/form/blob/b82093350ae986ad6c65a9ad25bf748efa53d7be/sources/sort.c#L2236
whether we are doing a regular or sub-buffer sort. If this information is known, the error message can be printed with "Sub", accordingly.

Also the user may not be using a form.set file, maybe the error should just refer generically to the "(Sub)SmallExtension setup parameter".

[tueda]

Right. In this case,

#: SubSmallExtension 15M

is needed, indeed.