Instead of adding "ifs" to each line, you could try to use the null coalescing operator "??" (which internally involves an if statement, but is much more elegant and readable). The format would be (I take just one line as an example):
<table><tbody><tr><td>@item.prototype_category.prototype_category_name ?? ""</td></tr></tbody></table>
Of course, I'm assuming the data type of prototype_category_name is a string, otherwise you will have an error. This will replace a null value with an empty string, which will just leave an empty cell. Of course, you might want to replace the empty string with something else to indicate that the cell is empty...
--AFP