Bar Chart: Crash when no number field exist (#102265)

* fix bar chart crash

* format

* use optional chaining

public/app/plugins/panel/barchart/utils.ts

@@ -247,7 +247,7 @@ export const prepConfig = ({ series, totalSeries, color, orientation, options, t
       // use opacity from first numeric field
       let opacityField = frame.fields.find((f) => f.type === FieldType.number)!;
 
-      fillOpacity = (opacityField.config.custom.fillOpacity ?? 100) / 100;
+      fillOpacity = (opacityField?.config?.custom?.fillOpacity ?? 100) / 100;
 
       getColor = (seriesIdx: number, valueIdx: number) => {
         let field = frame.fields[seriesIdx];