fix(scale): #20265 when dataZomm.filterMode is “empty” or ‘none’， the line graph is scaled to only one category, it is not filtered correctly

src/scale/helper.ts

@@ -128,7 +128,7 @@ export function contain(val: number, extent: [number, number]): boolean {
 
 export function normalize(val: number, extent: [number, number]): number {
     if (extent[1] === extent[0]) {
-        return 0.5;
+        return isNaN(val) ? NaN : 0.5;
     }
     return (val - extent[0]) / (extent[1] - extent[0]);
 }