[Rockyrok77]

With the decimal feature, tan on a decimal number panics when the result overflows:

parse_decimal("1.5707963267948966192313216916").tan();   // π/2: panics with "Tan overflowed"

decimal_functions::tan calls rust_decimal's MathematicalOps::tan, which panics whenever checked_tan returns None. That happens at π/2 (and 3π/2), where the reciprocal it takes divides by zero. The panic comes from inside a native function, so no engine limit stops it, and a script can take down the host with one call. sqrt, exp, ln and log10 in the same module already use the checked forms and raise ErrorArithmetic; tan now does the same. sin and cos were checked too: their checked_ forms cannot return None for any Decimal, so they are left alone.

Added test_math_decimal_tan to tests/math.rs. Without the fix it panics; with it, it passes. cargo test --tests passes with default features and with the decimal, no_float,decimal, decimal,unchecked, only_i32,decimal and decimal,serde,metadata,internals,debugging,grain rows of the CI matrix; cargo fmt --check and the CI clippy invocation are clean. CHANGELOG line under 1.27.1's bug fixes.

[schungx]

There are merge conflicts. Can you fix? Thanks!