This apply is called by the parser package when a parsing error occurs,
allowing the mudlib to provide custom error messages for parse_sentence()
failures.
**Arguments:**
- `error_type`: The type of parsing error that occurred
- `ob`: The object that caused the error (may be 0)
- Additional arguments depend on the error type
**Error Types and Arguments:**
- `ERR_IS_NOT` / `ERR_NOT_LIVING` / `ERR_NOT_ACCESSIBLE` (4 arguments):
- `string noun`: The noun that caused the error
- `int is_plural`: 1 if plural, 0 if singular
- `ERR_AMBIG` (3 arguments):
- `object *objects`: Array of ambiguous objects
- `ERR_ORDINAL` (3 arguments):
- `int ordinal`: The problematic ordinal number
- `ERR_THERE_IS_NO` (3 arguments):
- `string phrase`: The problematic word sequence
- `ERR_ALLOCATED` (3 arguments):
- `string message`: An allocated error string
- `ERR_BAD_MULTIPLE` (2 arguments):
- (no additional arguments)
- `ERR_MANY_PATHS` (5 arguments):
- (additional path-related data)
**Return Value:**
- Return a string containing the error message to show to the user
- Return 0 to use default error handling