Fix zero-step SVG arc rendering for thin strokes in turtle-painter

[kartikktripathi]

Summary

This PR fixes an incorrect use of Math.floor() in turtle-painter.js that allowed arc step calculations to become zero for thin stroke values. This silently broke SVG arc cap rendering for hollow lines and bezier curves.

Changes

1. Corrected improper Math.floor usage where the minimum guard was mistakenly passed as a second argument:

   • Before:
     const steps = Math.max(Math.floor(savedStroke, 1));

   • After:
     const steps = Math.max(Math.floor(savedStroke), 1);

2. Applied the same fix consistently in all four affected locations:

   • Line 349
   • Line 367
   • Line 607
   • Line 1041

This ensures that steps is always at least 1, preventing _svgArc() from receiving 0 steps.

Testing

1. Set very thin pen sizes (e.g., 0.5, 1).
2. Drew hollow lines, SVG arcs, and bezier curves.
3. Verified:
   • No zero-step arcs
   • Proper round cap rendering
   • No regression in normal stroke rendering

Note

Math.floor(x, 1) ignores the second argument in JavaScript. The previous implementation effectively allowed steps to become 0, causing silent rendering issues. This fix enforces the intended minimum guard correctly.

[github-actions]

✅ All Jest tests passed! This PR is ready to merge.

[kartikktripathi]

Hey @walterbender, this PR is ready to be reviewed. It fixes the incorrect use of Math.floor().
Thanks!

[mahesh-09-12]

@kartikktripathi nice catch here, the previous Math.floor(savedStroke, 1) usage was incorrect and could result in zero steps for thin strokes. Clamping the computed value with Math.max(..., 1) makes the SVG arc rendering more robust and prevents subtle visual issues. The change is minimal and applied consistently.

[kartikktripathi]

Thanks for the review, Mahesh!

[7se7en72025]

LGTM @walterbender