Fixes for numeric planning

[DillonZChen]

Proposed changes

Fix the minus expression for parsing domains.

As an example the code

from pddl.parser.domain import DomainParser

domain = DomainParser()(
    """
;; https://github.com/ipc2023-numeric/ipc2023-dataset/blob/main/block-grouping/domain.pddl
;; Enrico Scala (enricos83@gmail.com) and Miquel Ramirez (miquel.ramirez@gmail.com)

(define (domain mt-block-grouping)
    (:requirements :typing :numeric-fluents)
    (:types block - object )
    (:functions
        (x ?b - block)  ;; The position of a block
        (y ?b - block)  ;;
        (max_x)
        (min_x)
        (max_y)
        (min_y)
    )

    ;; Move a block from its location to an adjacent location
    (:action move_block_up
     :parameters (?b - block)
     :precondition (and (<= (+ (y ?b)1) (max_y) ))
     :effect (and
        (increase (y ?b) 1)
    ))

    (:action move_block_down
     :parameters (?b - block)
     :precondition (and (>= (- (y ?b) 1) (min_y) ))
     :effect (and
        (decrease (y ?b) 1)
    ))

    (:action move_block_right
     :parameters (?b - block)
     :precondition (and (<= (+ (x ?b)1) (max_x) ))
     :effect (and
        (increase (x ?b) 1)
    ))

    (:action move_block_left
     :parameters (?b - block)
     :precondition (and (>= (- (x ?b) 1) (min_x) ))
     :effect (and
        (decrease (x ?b) 1)
    ))
)
"""
)

causes the error

KeyError: 'NUMBER'

During handling of the above exception, another exception occurred:

lark.exceptions.UnexpectedToken: Unexpected token Token('NUMBER', '1') at line 26, column 39.
Expected one of: 
	* RPAR

Fixes

Remove a seemingly unnecessary line in the lark file

Types of changes

What types of changes does your code introduce?
Put an x in the boxes that apply

• Bugfix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)

Checklist

Put an x in the boxes that apply.

• I have read the CONTRIBUTING doc
• Lint and unit tests pass locally with my changes
• I have added tests that prove my fix is effective or that my feature works

Further comments

Added some fixtures to the tests and they all pass.

[DillonZChen]

Oh I just realised this is the same issue as #104.