[CS] Eagerly bind hole in recordInvalidNode

We know this is where the issue is so we can immediately bind to a hole,
ensuring we don't produce unnecessary downstream diagnostics from
things we can't infer.

lib/Sema/CSSimplify.cpp

@@ -6694,6 +6694,10 @@ bool ConstraintSystem::repairFailures(
   }
 
   case ConstraintLocator::Condition: {
+    // If the condition is already a hole, we're done.
+    if (lhs->isPlaceholder())
+      return true;
+
     if (repairViaOptionalUnwrap(*this, lhs, rhs, matchKind, conversionsOrFixes,
                                 locator))
       return true;