Bugfix: arraysize on Error shall be int, had wrong type

We might consider some type of consolidation to define identical
concepts in one place - for example many items need a datatype
definition.  But, comparing to Error to Argument, for example, one
difference is that the Error item is optionally named but Arguments must
be named.

ifex/model/ifex_ast.py

@@ -111,7 +111,7 @@ class Error:
  description: Optional[str] = str()
  """ Specifies a description of how the errors shall be used. """
 
- arraysize: Optional[str] = None
+ arraysize: Optional[int] = None
  """
  Specifies the number of elements in the input parameter array.
  This key is only allowed if the datatype element specifies an array (ending with []).