Expect exception for a symbol we can't calculate the charge for - e.g. 'As' in this case.

Change-Id: Ie45700c65312c8ef2a48d3cf818a1e5f373a97b1
Signed-off-by: Egon Willighagen <egonw@users.sourceforge.net>
Throw an exception if the symbol isn't supported.

Change-Id: Iab010551e605457f1b1120a253a7f5dcbaa500c4
Signed-off-by: Egon Willighagen <egonw@users.sourceforge.net>