Prevent using prototype properties as units

[goto-bus-stop]

If you try to use "1arguments", the code attempts to access parse.arguments, which throws an error in strict mode. If you try to use "2call", parse returns NaN, because it tries to use the parse.call function value in the calculation.

With this change, prototype properties are not considered when resolving units.

[dy]

@goto-bus-stop do you think this would be better?
units = !Function.prototype[units] && (parse[units] || parse[units.replace(/s$/, '')])
seems one less check and shorter

[goto-bus-stop]

Then argumentss would trigger it (Function.prototype.argumentss does not exist, but then it does parse['argumentss'] || parse['arguments']). Also, accessing the arguments property on the prototype also throws an error:

~ > node -e 'Function.prototype.arguments'
[eval]:1
Function.prototype.arguments
                   ^

TypeError: 'caller', 'callee', and 'arguments' properties may not be accessed on strict mode functions or the arguments objects for calls to them
    at [eval]:1:20
    at runScriptInThisContext (node:internal/vm:209:10)
    at node:internal/process/execution:459:12
    at [eval]-wrapper:6:24
    at runScriptInContext (node:internal/process/execution:457:60)
    at evalFunction (node:internal/process/execution:285:30)
    at evalTypeScript (node:internal/process/execution:297:3)
    at node:internal/main/eval_string:71:3

Node.js v23.6.0

[goto-bus-stop]

that is to say, i favour the straightforward, "correct" but longer way :)

[dy]

@goto-bus-stop as a second thought, I wonder if parse.unit = {...} would be a better option here, instead of storing units on parse function directly.