Handle invalid Crashpad handler path (#97)

* Hanle invalid Crashpad handler path

* Use helper instead of File + fix typo

Author: konraddysput

backtrace-library/src/main/java/backtraceio/library/BacktraceDatabase.java

@@ -177,8 +177,11 @@ public Boolean setupNativeIntegration(BacktraceBase client, BacktraceCredentials
         }
         // Path to Crashpad native handler
         String handlerPath = _applicationContext.getApplicationInfo().nativeLibraryDir + _crashpadHandlerName;
+        if (!FileHelper.isFileExists(handlerPath)) {
+            return false;
+        }
 
-        // setup default native attribtues
+        // setup default native attributes
         BacktraceAttributes crashpadAttributes = new BacktraceAttributes(_applicationContext, client.attributes);
         crashpadAttributes.attributes.put(BacktraceAttributeConsts.ErrorType, BacktraceAttributeConsts.CrashAttributeType);
         String[] keys = crashpadAttributes.attributes.keySet().toArray(new String[0]);