feat(setLegend): error if non-rectangular bitmap

src/shared/sprig_engine/engine.js

@@ -61,6 +61,14 @@ exports.clearText = () => native.text_clear();
 
 exports.setLegend = (...bitmaps) => {
   native.legend_clear();
+
+  for (const [key, bitmap] of bitmaps) {
+    const rows = bitmap.trim().split("\n").map(x => x.trim())
+    const rowLengths = rows.map(x => x.length);
+    const isRect = rowLengths.every(val => val === rowLengths[0])
+    if (!isRect) throw new Error(`Bitmap with key ${key} is not rectangular.`)
+  }
+
   for (const [charStr, bitmap] of bitmaps) {
     native.legend_doodle_set(charStr, bitmap.trim());
   }