Fix: Remove nullable type hints from callable parameters in Result class

[t1sh0o]

Description

This PR fixes the issue described in #42 regarding PHPStan v1 errors with nullable callable parameters.

Problem

The callable parameters in Result methods were incorrectly marked as nullable (T=) when they should be required (T). This was causing PHPStan v1 to report errors about parameter mismatches.

Solution

Removed the = from all callable parameter type hints in the Result abstract class. Since these callables are only invoked when there's an actual value present (Ok for map/andThen, Err for mapErr/orElse), the parameters should not be nullable.

Changes

• Updated all callable parameter type hints from callable(T=) to callable(T)
• Updated all callable parameter type hints from callable(E=) to callable(E)

Testing

• ✅ All unit tests pass
• ✅ Static analysis with Psalm passes
• ✅ Code style checks pass

Fixes #42

[tminich]

Looks good, I would suggest though to make some of the methods more flexible:

        /**
         * Calls op if the result is Ok, otherwise returns the Err value of self.
         *
         * @template U
         * @template F
         *
         * @param callable(T):Result<U,F> $op
         * @return Result<U,E|F>
         */
        public function andThen(callable $op): self;
        /**
         * Calls op if the result is Err, otherwise returns the Ok value of self.
         *
         * @template U
         * @template F
         *
         * @param callable(E):Result<U,F> $op
         * @return Result<T|U,F>
         */
        public function orElse(callable $op): self;

        /**
         * Unwraps a result, yielding the content of an Ok. Else, it returns optb.
         *
         * @template U
         *
         * @param U $optb
         * @return T|U
         */
        public function unwrapOr($optb): mixed;

        /**
         * Unwraps a result, yielding the content of an Ok. If the value is an Err then it calls op with its value.
         *
         * @template U
         *
         * @param callable(E):U $op
         * @return T|U
         */
        public function unwrapOrElse(callable $op): mixed;

[t1sh0o]

@tminich done

[prewk]

Wow, you fixed the CI ✨