fix(editor): allow editing of null stop times

lib/editor/components/timetable/TimetableGrid.js

@@ -271,8 +271,43 @@ export default class TimetableGrid extends Component {
     )
   }
 
+  /**
+   * Handle a change in the value of a cell.
+   *
+   * This function gets called with a post-processed value from the `save`
+   * method of EditableCell.  The value can be a time value or non-time entry
+   * such as Trip Id or Headsign.
+   */
   _onCellChange = (value, rowIndex, col, colIndex) => {
-    const {columns, hideDepartureTimes, updateCellValue} = this.props
+    const {
+      activePattern,
+      columns,
+      data,
+      hideDepartureTimes,
+      updateCellValue
+    } = this.props
+
+    // determine if the value is a time entry
+    if (isTimeFormat(col.type)) {
+      // make sure stop time isn't null
+      const splitColKeys = col.key.split('.')
+      const stopTimeIdx = splitColKeys[1]
+      const trip = data[rowIndex]
+      const stopTime = trip.stopTimes[stopTimeIdx]
+      if (!stopTime) {
+        // stop time is null.  Create new stop time
+
+        // get stop id from pattern
+        const {stopId} = activePattern.patternStops[stopTimeIdx]
+
+        // create filler stop time object
+        updateCellValue(
+          { stopId },
+          rowIndex,
+          `${rowIndex}.stopTimes.${stopTimeIdx}`
+        )
+      }
+    }
     updateCellValue(value, rowIndex, `${rowIndex}.${col.key}`)
     // if departure times are hidden, set departure time value equal to arrival time
     const nextCol = columns[colIndex + 1]