diff --git a/src/d3wave.tsx b/src/d3wave.tsx
index 2e39696..fcc98b5 100644
--- a/src/d3wave.tsx
+++ b/src/d3wave.tsx
@@ -3,30 +3,25 @@ import { useRef, useId, useEffect } from 'react';
 import * as d3 from 'd3';
 import { WaveGraph } from 'd3-wave';
 import { RowRendererBits } from 'd3-wave';
-import { AnyWaveGraphValue, WaveGraphSignalTypeInfo} from 'd3-wave';
 
-export const STRING_FORMAT: { [formatName: string]: (d: AnyWaveGraphValue) => string } = {
-	"STRING": (d: AnyWaveGraphValue) => d.toString(),
-}
-
-/**
- * A renderer for string value row
- */
 export class RowRendererString extends RowRendererBits {
-	constructor(waveGraph: WaveGraph) {
-		super(waveGraph);
-		this.FORMATTERS = STRING_FORMAT;
-		this.DEFAULT_FORMAT = STRING_FORMAT.STRING;
-	}
-	select(typeInfo: WaveGraphSignalTypeInfo) {
-		return typeInfo.name === 'string';
-	}
-	render(parent: d3.Selection<SVGGElement, any, any, any>, data: SignalDataValueTuple[], typeInfo: WaveGraphSignalTypeInfo, formatter?: string | ((d: AnyWaveGraphValue) => string)) {
-		super.render(parent, data, typeInfo, formatter);
-	}
-	isValid(d: any) {
-		return true;
-	}
+  constructor(waveGraph: WaveGraph) {
+    super(waveGraph);
+    // @ts-ignore
+    this.FORMATTERS = {
+      "STRING": (data: { toString(): string }) =>
+        data.toString()
+    };
+    this.DEFAULT_FORMAT = this.FORMATTERS.STRING;
+  }
+
+  select(typeInfo: { name: string }) {
+    return typeInfo.name === 'string';
+  }
+
+  isValid(data: any) {
+    return true;
+  }
 }
 
 export interface ViewerProps {
@@ -45,12 +40,12 @@ export function Viewer(props: ViewerProps) {
     }
     waveGraphRef.current.setSizes();
 
-    const resizeObserver = new ResizeObserver((events) => waveGraphRef.current.setSizes());
+    const resizeObserver = new ResizeObserver((events) => waveGraphRef.current?.setSizes());
     resizeObserver.observe(imageRef.current!);
     return () => resizeObserver.disconnect();
   }, []);
 
   useEffect(() => waveGraphRef.current?.bindData(props.data), [props.data]);
 
-  return <svg width="100%" height="100%" style={{ display: 'block' }} id={imageId} ref={imageRef}/>;
+  return <svg width="100%" height="100%" style={{ display: 'block' }} id={imageId} ref={imageRef} />;
 }