Fix NumberInput when displayValue is NaN

modules/client/components/NumberTextInput.js

@@ -31,8 +31,10 @@ class NumberTextInput extends React.Component {
     const { value } = this.state
     const displayValue = this.props.formatNumber(value)
 
+    const inputValue = isNaN(displayValue) ? 0 : displayValue
+
     return (
-      <input {...this.props} type="text" value={displayValue} onChange={this.handleChange}/>
+      <input {...this.props} type="text" value={inputValue} onChange={this.handleChange}/>
     )
   }
 }