throw error if there are no builds when rendering

Signed-off-by: Jakub Sokołowski <jakub@status.im>

src/app.js

@@ -29,7 +29,9 @@ const App = (ghc) => {
       body: ghc.db.schema,
     },
     handler: async (ctx) => {
+      /* save the build */
       await ghc.db.addBuild(ctx.params.pr, ctx.request.body)
+      /* post or update the comment */
       await ghc.update(ctx.params.pr)
       ctx.status = 201
       ctx.body = {status:'ok'}

src/comments.js

@@ -20,6 +20,9 @@ class Comments {
 
   async renderComment (pr) {
     const builds = await this.db.getBuilds(pr)
+    if (builds.length == 0) {
+      throw Error('No builds exist for this PR')
+    }
     return this.nj.renderString(this.template, {builds})
   }