resolves#100

• Updated the handling of color scales to use a newunknown color value (#cccccc99) for invalid data, ensuring better visual distinction in plots. (src/lib/core/Plot.svelte,[1][2]
• Adjusted the logic for validating color scale values inMark.svelte to improve handling of invalid data points. (src/lib/Mark.svelte,src/lib/Mark.svelteL261-R271)
• Changed the default class name forDot marks from "dots" to "dot" for better consistency. (src/lib/marks/Dot.svelte,src/lib/marks/Dot.svelteL87-R86)

Examples and Documentation:

• Added a new example for a "Bubble matrix" plot, showcasing grouped data visualization withDot marks. (src/routes/examples/dot/bubble-matrix.svelte,src/routes/examples/dot/bubble-matrix.svelteR1-R27)
• Enhanced the homepage with a new "Examples" action button linking to the examples section. (src/routes/+page.md,src/routes/+page.mdL8-R15)

Testing Infrastructure Updates:

New Tests:

• Introduced a dedicated test forDot marks, validating rendering, scaling, and color mapping based on data. (src/tests/dot.test.svelte,[1];src/tests/dot.test.ts,[2]

Utility Functions:

• Added reusable utility functions (getRectDims,getPathDims,getTranslate) for extracting dimensions and transformations from SVG elements, improving test reliability and modularity. (src/tests/utils.ts,src/tests/utils.tsR1-R40)
• Refactored existingBarX tests to replace inline dimension calculation functions with the new utility functions. (src/tests/barX.test.ts,[1][2]

Code Quality Improvements:

ESLint Configuration:

• Added a new rule to disallowconsole.log while permittingconsole.error. (eslint.config.js,eslint.config.jsR6-R16)
• Introduced thesvelte/no-inspect rule to warn against using the inspect directive in Svelte files. (eslint.config.js,eslint.config.jsR6-R16)

Refactoring:

• Removed unused methods (updateMark,updatePlotState) fromMark.svelte to streamline the codebase. (src/lib/Mark.svelte,src/lib/Mark.svelteL59-R59)
• Adjusted theColorLegend styling to include column gaps for better spacing. (src/lib/marks/ColorLegend.svelte,src/lib/marks/ColorLegend.svelteR170)