fix: use expression to generalize zeroOrMinOrMax when there is a scale

src/compile/mark/encode/zeroOrMinOrMax.ts

@@ -20,6 +20,21 @@ export function zeroOrMinOrMax({
     };
   }
 
+  if (scaleName) {
+    const domain = `domain('${scaleName}')`;
+    const min = `${domain}[0]`;
+    const max = `peek(${domain})`; // peek = the last item of the array
+
+    switch (mode) {
+      case 'min':
+        return {signal: `scale('${scaleName}', ${min})`}; // encode the scale domain min
+      case 'zeroOrMin':
+        return {signal: `scale('${scaleName}', inrange(0, ${domain}) ? 0 : ${min})`}; // encode the scale domain min
+      default: //zeroOrMax
+        return {signal: `scale('${scaleName}', inrange(0, ${domain}) ? 0 : ${max})`}; // encode the scale domain max
+    }
+  }
+
   if (mode === 'zeroOrMin' || mode === 'min') {
     switch (mainChannel) {
       case 'radius':
@@ -29,7 +44,7 @@ export function zeroOrMinOrMax({
       case 'y':
         return {field: {group: 'height'}};
       default:
-        return {signal: `scale('${scaleName}', domain('${scaleName}')[0])`}; // encode the scale domain min
+        return undefined; // For non-position, it's impossible to reach this line if the field doesn't have a scale.
     }
   } else {
     // zeroOrMax
@@ -48,7 +63,7 @@ export function zeroOrMinOrMax({
       case 'y':
         return {value: 0};
       default:
-        return {signal: `scale('${scaleName}', domain('${scaleName}')[1])`}; // encode the scale domain max
+        return undefined; // For non-position, it's impossible to reach this line if the field doesn't have a scale.
     }
   }
 }