Overall Technical Inqury

Hi, There. I did migration myself using official migration tool.
I have some price issue. If i use your extension, is there no issue like this ?
We are about to migrate 1.9.1.0. to 2.1.9
 
#1, We have an issue about showing price 
http://dev.kbethos.com/blanks-classics.html
 
Preconditions

1. I migrated data from 1.9.1.0 to 2.1.9
2. There are multiple stores at Magento1
3. I’m testing Magento2 right away before launching M2
4. I set display out of stock product as NO in admin page on M2.

Steps to reproduce

1. For example, i have 3 multiple store called A,B,C on M2
2. Make a grouped product which has a associated products under various condition. (reference #3)
3. When a associated product are a member of only website B, it has quantity and is enabled, rest of them are disabled and are members of website A , you can see this error on A website frontend.

Expected result

1. The grouped product shouldn’t be shown on A website because i set the display none about out-of-stock item.

Actual result

1. [Screenshot, logs]

Fatal error: Uncaught Error: Call to a member function getPriceInfo() on null in /home/staging/public_html/vendor/magento/module-grouped-product/Pricing/Price/FinalPrice.php:34 
Stack trace: 
#0 /home/staging/public_html/vendor/magento/module-msrp/Helper/Data.php(167): Magento\GroupedProduct\Pricing\Price\FinalPrice->getValue() 
#1 /home/staging/public_html/vendor/magento/module-msrp/Pricing/Price/MsrpPrice.php(101): Magento\Msrp\Helper\Data->isMinimalPriceLessMsrp(Object(Magento\Catalog\Model\Product\Interceptor)) 
#2 /home/staging/public_html/vendor/magento/module-catalog/Pricing/Render/FinalPriceBox.php(124): Magento\Msrp\Pricing\Price\MsrpPrice->isMinimalPriceLessMsrp(Object(Magento\Catalog\Model\Product\Interceptor)) 
#3 /home/staging/public_html/vendor/magento/module-catalog/Pricing/Render/FinalPriceBox.php(81): Magento\Catalog\Pricing\Render\FinalPriceBox->isMsrpPriceApplicable() 
#4 /home/staging/public_html/vendor/magento/framework/View/Element/AbstractBlock.php(659): Magento\Catalog\Pricing\Render\FinalPriceBox->_toHt in /home/staging/public_html/vendor/magento/module-grouped-product/Pricing/Price/FinalPrice.php on line 34

On Magento1, When i set the a product configuration like this

We can’t see a grouped product(e.g. KBSV-AZ) on a wh website because associated products from wh are out of stock even associated product from another website (e.g. retail) are in-stock and have few quantity.
It truly makes sense because i set the display out-of-stock product as NO on Magento1.
BTW on Magento2, it is saying a error message on same environment like this

i can even see this product on frontend although we set display out-of-stock as No. I assume that this is a migrated Magento 2 and it followed M1 configuration perfectly. But this is not launching website and i put the base url for another website(retail) as fake url. So Does it affect this problem?
What do you think about this root problem? Thank you
 
#2, Original price doesn’t show up with customer group price like this on most products. 
 

 
How can i handle this problem?