Use instanceof

Author: owen-mc

java/ql/lib/semmle/code/java/controlflow/UnreachableBlocks.qll

@@ -211,7 +211,7 @@ class UnreachableBasicBlock extends BasicBlock {
     // expression in an assert statement, or a catch clause.
     forall(BasicBlock bb | bb = this.getABBPredecessor() | bb instanceof UnreachableBasicBlock) and
     not exists(Callable c | c.getBody().getControlFlowNode() = this.getFirstNode()) and
-    not exists(AssertStmt a | a = this.getFirstNode().asExpr().getEnclosingStmt()) and
+    not this.getFirstNode().asExpr().getEnclosingStmt() instanceof AssertStmt and
     not this.getFirstNode().asStmt() instanceof CatchClause
     or
     // Switch statements with a constant comparison expression may have unreachable cases.