Incorrect conversion of number to boolean

Check for min/max/stepSize coerces numbers to truthy values. A min setting of 0 is therefore interpreted as not being set.

Checking against undefined means settings are correctly detected.

src/scales/scale.linearbase.js

@@ -25,7 +25,7 @@ function generateTicks(generationOptions, dataRange) {
  var niceMax = Math.ceil(dataRange.max / spacing) * spacing;
 
  // If min, max and stepSize is set and they make an evenly spaced scale use it.
- if (generationOptions.min && generationOptions.max && generationOptions.stepSize) {
+ if (generationOptions.min !== undefined && generationOptions.max !== undefined && generationOptions.stepSize !== undefined) {
  // If very close to our whole number, use it.
  if (helpers.almostWhole((generationOptions.max - generationOptions.min) / generationOptions.stepSize, spacing / 1000)) {
  niceMin = generationOptions.min;