getcolors.js mutates caller-provided frameColor / iconColor / colorMode objects in-place

[JohnPHowe]

Summary

getcolors.js directly mutates the objects passed in via style.colorMode,
style.frameColor, and style.iconColor rather than working on copies. When a
caller reuses any of those objects across multiple Symbol() calls, mutations
from one render corrupt subsequent renders.

Affected file

src/ms/symbol/getcolors.js

What happens

Lines 3–14 assign the caller's objects to local variables by reference:

let baseFillColor =
  typeof this.style.colorMode === "object"
    ? this.style.colorMode          // ← same object the caller owns
    : ms.getColorMode(this.style.colorMode);
const baseFrameColor =
  typeof this.style.frameColor === "object"
    ? this.style.frameColor         // ← same object the caller owns
    : ms.getColorMode("FrameColor");
const baseIconColor =
  typeof this.style.iconColor === "object"
    ? this.style.iconColor          // ← same object the caller owns
    : ms.getColorMode("IconColor");

Lines 22–48 then mutate those variables directly:

// civilian branch
baseFillColor.Friend = baseFillColor.Neutral = baseFillColor.Unknown = baseFillColor.Civilian;
baseFrameColor.Friend = baseFrameColor.Neutral = baseFrameColor.Unknown = baseFrameColor.Civilian;

// joker/faker branch
baseFillColor.Friend = baseFillColor.Hostile;
baseFrameColor.Friend = baseFrameColor.Hostile;

// suspect branch
baseFillColor.Friend = baseFillColor.Hostile = baseFillColor.Suspect;
baseFrameColor.Friend = baseFrameColor.Hostile = baseFrameColor.Suspect;

// monoColor branch
baseFrameColor.Friend = baseFrameColor.Neutral = baseFrameColor.Hostile = ... = this.style.monoColor;

Because these are in-place property assignments on the original object, the
caller's shared color-mode object is permanently altered after any civilian,
joker, faker, suspect, or monoColor symbol renders.

Reproduction

import ms from 'milsymbol';

const colorMode = ms.getColorMode('Light'); // shared object

// First render: a Suspect symbol — mutates colorMode.Friend
new ms.Symbol('10031500001101000000', { colorMode }).asSVG();

// Second render: a Friend symbol — colorMode.Friend is now corrupted
// to the Suspect value, so this renders with the wrong color
new ms.Symbol('10031000001101000000', { colorMode }).asSVG();

The same issue occurs with any object literal passed as colorMode,
frameColor, or iconColor and reused across calls — a common pattern
when rendering a grid of symbols with a shared color theme.

Fix

Shallow-clone the incoming objects before mutating:

let baseFillColor = {
  ...(typeof this.style.colorMode === "object"
    ? this.style.colorMode
    : ms.getColorMode(this.style.colorMode))
};
const baseFrameColor = {
  ...(typeof this.style.frameColor === "object"
    ? this.style.frameColor
    : ms.getColorMode("FrameColor"))
};
const baseIconColor = {
  ...(typeof this.style.iconColor === "object"
    ? this.style.iconColor
    : ms.getColorMode("IconColor"))
};

One spread per variable; no downstream behavior changes.

[spatialillusions]

Pull request is welcomed for this, it should probably include updated tests to verify the behavior.