Fix build if keystore.config file is missing

Author: danopdev

app/build.gradle

@@ -6,13 +6,16 @@ plugins {
 android {
     signingConfigs {
         'default' {
-            Properties keystoreProps = new Properties()
-            keystoreProps.load(new FileInputStream(file('keystore.config')))
+            File keystoreConfigFile = file('keystore.config')
+            if (keystoreConfigFile.exists()) {
+                Properties keystoreProps = new Properties()
+                keystoreProps.load(new FileInputStream(file('keystore.config')))
 
-            keyAlias keystoreProps['keyAlias']
-            keyPassword keystoreProps['keyPassword']
-            storePassword keystoreProps['storePassword']
-            storeFile file(keystoreProps['storePath'])
+                keyAlias keystoreProps['keyAlias']
+                keyPassword keystoreProps['keyPassword']
+                storePassword keystoreProps['storePassword']
+                storeFile file(keystoreProps['storePath'])
+            }
         }
     }