Merge pull request #521 from github/fixes/516-handle-bad-json-gracefully

Handle IO and json exceptions gracefully

Author: shana

src/GitHub.Exports/Services/UsageTracker.cs

@@ -42,8 +42,25 @@ public UsageTracker(
             [Import(typeof(SVsServiceProvider))] IServiceProvider serviceProvider)
         {
             fileExists = (path) => System.IO.File.Exists(path);
-            readAllText = (path, encoding) => System.IO.File.ReadAllText(path, encoding);
-            writeAllText = (path, content, encoding) => System.IO.File.WriteAllText(path, content, encoding);
+            readAllText = (path, encoding) =>
+            {
+                try
+                {
+                    return System.IO.File.ReadAllText(path, encoding);
+                }
+                catch
+                {
+                    return null;
+                }
+            };
+            writeAllText = (path, content, encoding) =>
+            {
+                try
+                {
+                    System.IO.File.WriteAllText(path, content, encoding);
+                }
+                catch {}
+            };
             dirCreate = (path) => System.IO.Directory.CreateDirectory(path);
 
             this.connectionManager = connectionManager;
@@ -138,9 +155,18 @@ public void IncrementLoginCount()
 
         UsageStore LoadUsage()
         {
-            var result = fileExists(storePath) ?
-                SimpleJson.DeserializeObject<UsageStore>(readAllText(storePath, Encoding.UTF8)) :
-                new UsageStore { Model = new UsageModel() };
+            var json = fileExists(storePath) ? readAllText(storePath, Encoding.UTF8) : null;
+            UsageStore result = null;
+            try
+            {
+                result = json != null ?
+                    SimpleJson.DeserializeObject<UsageStore>(json) :
+                    new UsageStore { Model = new UsageModel() };
+            }
+            catch
+            {
+                result = new UsageStore { Model = new UsageModel() };
+            }
 
             result.Model.Lang = CultureInfo.InstalledUICulture.IetfLanguageTag;
             result.Model.AppVersion = AssemblyVersionInformation.Version;