[react-strict-animated] Fix incorrect error message for invalid mass in SpringAnimation

[adityasingh2400]

Summary

The mass validation in the SpringAnimation constructor throws the wrong error message. It reports a damping problem when an invalid mass is supplied, because the message was copy-pasted from the preceding damping check.

if (this.#damping <= 0) {
  throw new Error('Damping value must be greater than 0');
}
if (this.#mass <= 0) {
  throw new Error('Damping value must be greater than 0'); // should be Mass
}

A user passing mass: 0 (or a negative mass) gets told their damping value is wrong, which points them at the wrong config field. React Native's equivalent SpringAnimation throws 'Mass value must be greater than 0' here.

Fix

Use the correct message for the mass check.

Test

Added SpringAnimation-test.js covering all three constructor validations (stiffness, damping, mass). The mass case fails on main (asserts 'Mass value must be greater than 0') and passes with the fix.

flow check and eslint are clean.

---

Reopening this. I closed it by accident during a bulk cleanup of my stale forks and cannot reopen the original because the fork was deleted, so this is the same branch restored. Sorry for the noise @MoOx.

[github-actions]

workflow: benchmarks/perf (native)

Comparison of performance test results, measured in operations per second. Larger is better.

Results	Base	Patch	Ratio
css.create
· small	1,177,102	1,165,316	0.99	-
· small with units	518,029	522,422	1.01	+
· small with variables	699,492	698,237	1.00	-
· several small	375,307	371,936	0.99	-
· large	219,648	215,158	0.98	-
· large with polyfills	162,353	162,533	1.00	+
· complex	112,357	113,791	1.01	+
· unsupported	222,705	222,039	1.00	-
css.createTheme
· simple theme	245,202	245,589	1.00	+
· polyfill theme	232,172	232,003	1.00	-

[github-actions]

workflow: benchmarks/size

Comparison of minified (terser) and compressed (brotli) size results, measured in bytes. Smaller is better.

Results	Base	Patch	Ratio
react-strict-dom/dist/web/index.js
· compressed	3,251	3,251	1.00
· minified	10,375	10,375	1.00
react-strict-dom/dist/web/runtime.js
· compressed	1,645	1,645	1.00
· minified	4,131	4,131	1.00
react-strict-dom/dist/native/index.js
· compressed	16,618	16,705	1.01	+
· minified	64,626	64,818	1.00	+
react-strict-animated/dist/web/index.js
· compressed	6,861	6,855	1.00	-
· minified	23,486	23,483	1.00	-
react-strict-animated/dist/native/index.js
· compressed	797	797	1.00
· minified	2,518	2,518	1.00