change check logic of Project Config Builder

Author: wangjoshuah

OptimizelySDKCore/OptimizelySDKCore/OPTLYProjectConfig.m

@@ -54,7 +54,7 @@ + (nullable instancetype)initWithBuilderBlock:(nonnull OPTLYProjectConfigBuilder
 }
 
 - (instancetype)initWithBuilder:(OPTLYProjectConfigBuilder *)builder {
-    // check for valid error handler and logger
+    // check for valid error handler
     if (builder.errorHandler) {
         if (![OPTLYErrorHandler conformsToOPTLYErrorHandlerProtocol:[builder.errorHandler class]]) {
             NSError *error = [NSError errorWithDomain:OPTLYErrorHandlerMessagesDomain

OptimizelySDKCore/OptimizelySDKCore/OPTLYProjectConfigBuilder.m

@@ -27,17 +27,13 @@ - (id) init {
 }
 
 - (id)initWithBlock:(OPTLYProjectConfigBuilderBlock)block {
+    if (!_datafile) {
+        return nil;
+    }
     self = [super init];
     if (self != nil) {
         block(self);
     }
-    else {
-        return nil;
-    }
-    if (_datafile == nil) {
-        return nil;
-    }
-    
     return self;
 }