explicitly, rather than implicitly, default choropleth linewidth to 1

Author: alexcjohnson

src/components/drawing/index.js

@@ -112,7 +112,7 @@ drawing.lineGroupStyle = function(s, lw, lc, ld) {
 };
 
 drawing.dashLine = function(s, dash, lineWidth) {
-    lineWidth = lineWidth || 0;
+    lineWidth = +lineWidth || 0;
     var dlw = Math.max(lineWidth, 3);
 
     if(dash === 'solid') dash = '';

src/traces/choropleth/attributes.js

@@ -37,7 +37,7 @@ module.exports = extendFlat({}, {
     marker: {
         line: {
             color: ScatterGeoMarkerLineAttrs.color,
-            width: ScatterGeoMarkerLineAttrs.width
+            width: extendFlat({}, ScatterGeoMarkerLineAttrs.width, {dflt: 1})
         }
     },
     hoverinfo: extendFlat({}, plotAttrs.hoverinfo, {

src/traces/choropleth/plot.js

@@ -165,7 +165,7 @@ plotChoropleth.style = function(geo) {
                     d3.select(this)
                         .attr('fill', function(pt) { return sclFunc(pt.z); })
                         .call(Color.stroke, pt.mlc || markerLine.color)
-                        .call(Drawing.dashLine, '', pt.mlw || markerLine.width);
+                        .call(Drawing.dashLine, '', pt.mlw || markerLine.width || 0);
                 });
         });
 };