Add coverage for adding climb against existing climbs

Fix issue that popped up from coverage (new should be +1)

Author: greghart

src/model/MutableClimbDataSource.ts

@@ -110,16 +110,17 @@ export default class MutableClimbDataSource extends ClimbDataSource {
     // when adding new climbs, ensure they are added in expected sort order, such that:
     // * multiple climbs keep the order they're input in.
     // * all newly added climbs come after existing climbs.
-    let newClimbLeftRightIndex = (await this.climbModel
+    const maxExisting = (await this.climbModel
       .find({ _id: { $in: parent.climbs } })
       .select('metadata.left_right_index')
       .sort({ 'metadata.left_right_index': -1 })
-      .limit(1))[0]
-      ?.metadata.left_right_index ?? 1
+      .limit(1))[0]?.metadata.left_right_index
+    let newClimbLeftRightIndex = (maxExisting ?? 0) + 1
+
     function resolveLeftRightIndex (i: number): { left_right_index: number } | null {
       // user input is always prioritized
       if (userInput[i].leftRightIndex !== undefined) {
-        return { left_right_index: userInput[i].leftRightIndex! }
+        return { left_right_index: userInput[i].leftRightIndex ?? 0 }
       }
       // otherwise, auto-order new climbs
       if (!idList[i].existed) {

src/model/__tests__/MutableClimbDataSource.ts

@@ -212,7 +212,13 @@ describe('Climb CRUD', () => {
     ).rejects.toThrowError(/You can only add climbs to a crag/)
 
     // Route-only area should accept new boulder problems
-    await climbs.addOrUpdateClimbs(testUser, routesArea.metadata.area_id, [newBoulderProblem1])
+    const [newBoulderID] = await climbs.addOrUpdateClimbs(testUser, routesArea.metadata.area_id, [newBoulderProblem1])
+    // Should come after existing climbs
+    expect(await climbs.findOneClimbByMUUID(muid.from(newBoulderID))).toMatchObject({
+      metadata: {
+        left_right_index: newClimbsToAdd.length + 1
+      }
+    })
   })
 
   it('can add new boulder problems', async () => {