Added checks to make sure the specified track exists

Added precondition checks to validate input files and paths to return more informative error messages as per #2

src/edits.ts

@@ -33,6 +33,12 @@ export async function uploadRelease(options: EditOptions, releaseFile: string) {
         packageName: options.applicationId
     });
 
+    const allTracks = await getAllTracks(appEdit.data!, options);
+    if (allTracks == undefined || allTracks.find(value => value.track == options.track) == undefined) {
+        core.setFailed(`Track "${options.track}" could not be found `)
+        return Promise.reject(`No track found for "${options.track}"`)
+    }
+
     let track: Track | undefined = undefined;
     if (releaseFile.endsWith('.apk')) {
         const apk = await uploadApk(appEdit.data, options, releaseFile);
@@ -57,6 +63,15 @@ export async function uploadRelease(options: EditOptions, releaseFile: string) {
     }
 }
 
+async function getAllTracks(appEdit: AppEdit, options: EditOptions): Promise<Track[] | undefined> {
+    const res = await androidPublisher.edits.tracks.list({
+        auth: options.auth,
+        editId: appEdit.id!,
+        packageName: options.applicationId
+    });
+
+    return res.data.tracks
+}
 
 async function trackVersionCode(appEdit: AppEdit, options: EditOptions, versionCode: number): Promise<Track> {
     let status: string;

src/main.ts

@@ -1,4 +1,5 @@
 import * as core from '@actions/core';
+import * as fs from "fs";
 import {uploadRelease} from "./edits";
 const {google} = require('googleapis');
 
@@ -27,6 +28,22 @@ async function run() {
             userFractionFloat = undefined
         }
 
+        // Check release file
+        if (!fs.existsSync(releaseFile)) {
+            core.setFailed(`Unable to find release file @ ${releaseFile}`);
+            return
+        }
+
+        if (whatsNewDir != undefined && !fs.existsSync(whatsNewDir)) {
+            core.setFailed(`Unable to find 'whatsnew' directory @ ${whatsNewDir}`);
+            return
+        }
+
+        if (mappingFile != undefined && !fs.existsSync(mappingFile)) {
+            core.setFailed(`Unable to find 'mappingFile' @ ${mappingFile}`);
+            return
+        }
+
         // Insure that the api can find our service account credentials
         core.exportVariable("GOOGLE_APPLICATION_CREDENTIALS", serviceAccountJson);