Small improvements

src/map/map.ts

@@ -131,12 +131,19 @@ const DEFAULT_CONFIG = {
                     path: extractSvgPath(PNG_SVG),
                 },
                 click: function (gd: PlotlyScatterElement) {
+                    const width = Math.max(gd._fullLayout.width, 600);
+                    const ratio = gd._fullLayout.height / gd._fullLayout.width;
+                    const height = width * ratio;
+
                     Plotly.downloadImage(gd, {
                         filename: 'chemiscope-map',
                         format: 'png',
-                        width: Math.max(gd._fullLayout.width, 600),
-                        height: Math.max(gd._fullLayout.width, 600),
-                    }).catch((e: unknown) =>
+                        width: width,
+                        height: height,
+                        // scale is not part of `DownloadImgopts`, but accepted
+                        // by the function anyway
+                        scale: 3,
+                    } as unknown as Plotly.DownloadImgopts).catch((e: unknown) =>
                         setTimeout(() => {
                             throw e;
                         })

src/options.ts

@@ -81,9 +81,7 @@ export function optionValidator(valid: string[], name = ''): (value: string) =>
         if (valid.includes(value)) {
             return;
         }
-        throw Error(
-            `invalid property '${value}' for ${name}, are you sure the settings correspond to the current dataset?`
-        );
+        throw Error(`invalid value '${value}' for ${name}, expected one of [${valid.join(', ')}]`);
     };
 }