Setting segment_label#font-size to 0px causes transitive.js to crash

[landonreed]

@binh-dam-ibigroup, can you document some of the things that you tried/noticed about this when debugging?

[binh-dam-ibigroup]

Here are two quick things I tried that did not work at first and need further investigation:

At https://github.com/conveyal/transitive.js/blob/master/lib/labeler/labeler.js#L322

    if (label.fontSize) {
      // (Code in this block is unchanged)
      const textDimensions = measureText({
        text: labelText,
        // Append 'px' if a unit was not specified in font-size.
        fontSize: getFontSizeWithUnit(label.fontSize),
        fontFamily: label.fontFamily || 'sans-serif',
        lineHeight: 1.2
      })

      label.textWidth = textDimensions.width.value
      label.textHeight = textDimensions.height.value
      label.computeContainerDimensions()
    } else {
      label.textWidth = 1
      label.textHeight = 1
      label.containerWidth = 1
      label.containerHeight = 1
    }

    return label

At https://github.com/conveyal/transitive.js/blob/master/lib/labeler/segmentlabel.js#L34:

    if (fontSize) {
      // (Code in this block is unchanged)
      // Offset text location by padding
      display.drawText(text, {
        x: x + this.getPadding(),
        // Offset y by a couple of pixels to account for off-centeredness.
        y: y + this.getPadding() + 2
      }, {
        // text color
        fill: display.styler.compute2('segment_labels', 'color', this.parent),
        'font-family': display.styler.compute2('segment_labels', 'font-family', this.parent),
        // Append 'px' if a unit was not specified in font-size.
        'font-size': getFontSizeWithUnit(fontSize)
      })
    }
  }