The overflow check for safe signed subtraction was using the formula (rhs < 0) == (lhs > result). This logic is flawed and incorrectly reports an overflow when the right-hand side is zero.
For the expression 42 - 0, this check evaluated to (0 < 0) == (42 > 42), which is false == false, resulting in true. This caused the generated SPIR-V to incorrectly branch to an OpUnreachable instruction, preventing the result from being stored.

Fixes #24281.