diff --git a/public/classes/acecard_time_source.tsx b/public/classes/acecard_time_source.tsx
index 3a3f236..7432cb3 100644
--- a/public/classes/acecard_time_source.tsx
+++ b/public/classes/acecard_time_source.tsx
@@ -80,7 +80,7 @@ export class AcecardTimeLayerSource implements IMvtVectorSource {
     this._onRangeChange = this._onRangeChange.bind(this)
   }
   getFieldByName(fieldName: string): IField | null {
-    throw new Error('Method not implemented.');
+    return null
   }
   getLeftJoinFields(): Promise<IField[]> {
     throw new Error('Method not implemented.');
@@ -450,4 +450,4 @@ const TimeSlider = (props:{onChange:(value:[number,number])=>void,requestMeta:Ve
     setState(value)
     props.onChange(value);
   }} value={state}></EuiDualRange><div style={{height:"1em"}}><span style={{float:"left"}}>{startString.substring(0,startString.length-5)}</span><span style={{float:"right"}}>{stopString.substring(0,startString.length-5)}</span></div></div>
-}
\ No newline at end of file
+}