config: validate value and default of parameters

The Parameter Properties 'value', 'default' and 'constant'
have ValueType, so they are not checked in the setProperty call.
We have to do this explicitly in Module._add_accessible.

Change-Id: I1e35adf2fe539411b4aebacd813adb07497de95b
Reviewed-on: https://forge.frm2.tum.de/review/c/secop/frappy/+/35797
Tested-by: Jenkins Automated Tests <pedersen+jenkins@frm2.tum.de>
Reviewed-by: Alexander Zaft <a.zaft@fz-juelich.de>
Reviewed-by: Markus Zolliker <markus.zolliker@psi.ch>

frappy/modulebase.py

@@ -450,9 +450,12 @@ class Module(HasAccessibles):
             self.parameters[name] = accessible
         if isinstance(accessible, Command):
             self.commands[name] = accessible
-        if cfg:
+        if cfg is not None:
             try:
                 for propname, propvalue in cfg.items():
+                    if propname in {'value', 'default', 'constant'}:
+                        # these properties have ValueType(), but should be checked for datatype
+                        accessible.datatype(cfg[propname])
                     accessible.setProperty(propname, propvalue)
             except KeyError:
                 self.errors.append(f"'{name}' has no property '{propname}'")