Can I claim for indirect losses, like a deal I lost because of the seller's problem?

Sometimes, but indirect or consequential losses — like a separate deal you lost because of the seller's problem — are generally harder to recover than losses tied directly to the misrepresented or breached item itself. Damages typically have to be a reasonably foreseeable consequence of the breach, not simply any loss that eventually flowed from it however many steps removed, so a more remote loss faces a real hurdle even where causation seems clear to you.

Many purchase agreements also expressly exclude indirect, consequential, or special damages from what's recoverable under the indemnity provisions, which would foreclose a claim like this regardless of whether it was foreseeable, simply because the agreement itself carves it out. Whether this kind of loss can actually be claimed comes down closely to both general damages principles and, just as importantly, the specific wording of your purchase agreement's indemnity and limitation-of-liability clauses — review that language carefully before assuming either that this loss is automatically covered or automatically excluded.