fix(tickStep&logticks): prevent division by zero and handle invalid c…

[mishu2424]

fix(ticks): harden tick generation to prevent NaN/∞ and bad secondary ticks (bug #8194 )

Summary
This PR fixes two defects in tick generation that could produce non-finite numbers and misleading intermediate (secondary) log ticks.

Fix-1: Guard tickStep() against invalid count
Root cause: step0 = |stop - start| / Math.max(0, count) divides by 0 when count ≤ 0, yielding Infinity/NaN.

Change: Add a fail-fast guard to ensure count is a positive, finite number; throw a clear error otherwise.

Impact: Prevents non-finite values from propagating into axis/tick rendering and downstream math.

Fix-2: Stabilize secondary ticks in getLogTicks()
Root cause: Using secondaryTickCount directly could create an invalid window (start ≥ end) and/or a zero/too-small count between main ticks.

Change:
Clamp the effective secondary count: const adjustedTickCount = Math.max(1, secondaryTickCount - 2);
Generate secondary ticks within a margin inside the main-tick span to avoid touching endpoints:
ticks(
tick + rangeBetweenMainTicks / (secondaryTickCount + 1),
nextTick - rangeBetweenMainTicks / (secondaryTickCount + 1),
adjustedTickCount
)

Impact: Produces well-spaced, reproducible secondary ticks without overlapping main ticks or collapsing ranges.

Code changes
tickStep(start, stop, count)
if (count <= 0 || !Number.isFinite(count)) {
throw new Error('Count must be a positive finite number');
}

getLogTicks(start, stop, mainTickCount = 8, secondaryTickCount = 6)

const adjustedTickCount = Math.max(1, secondaryTickCount - 2);
// secondary window shrunk in from both ends; then symlog’ed

Checklist
-Fixes numerical instability in tickStep
-Stabilizes secondary tick generation in getLogTicks
-Lint & build passing locally
-Behavior unchanged for valid inputs