Yes, from the time a child is born they are taught that there are consequences for actions. This matter should be looked into and some penalty assessed against the DNC. Leaders should "lead" by example. Especially when officials are elected by the public to uphold laws and protect rights for the citizens that put them in office. Order begins from the top down. If anything, these leaders should be held to the highest of standards therefore facing the highest of responsibility for their actions.
No, the DNC should not be required to pay Bernie Sanders' campaign debts, despite the appearance of conspiracy against him. Sanders chose to run a campaign under the umbrella of the DNC. He could have run as an independent and had not only less risk of "conspiracy against him," but also less party support. Despite any inappropriate emails or thoughts against him but DNC officials (this is all we know so far), he benefited from running as a democrat.
The DNC should not pay Bernie Sanders' campaign debt, despite its role in blocking his nomination. Sanders knew he was facing an uphill battle for the nomination. The party can choose whomever it wishes under any rules it devises. Although politically embarrassing, the DNC is allowed to show favoritism in the selection process.
This conspiracy is a bigger deal than most are making of it, I believe. That many Sanders fans expected this sort of thing makes it less surprising, but no less important. I am not certain having the DNC pay campaign debts is the right thing to do here, but I believe a much greater emphasis should be placed on this wrong doing.