Cfg: Fix type.

csharp/ql/lib/semmle/code/csharp/controlflow/internal/ControlFlowGraph.qll

@@ -203,7 +203,7 @@ module Ast implements AstSig<Location> {
   final private class FinalTryStmt = CS::TryStmt;
 
   class TryStmt extends FinalTryStmt {
-    Stmt getBody(int index) { index = 0 and result = this.getBlock() }
+    AstNode getBody(int index) { index = 0 and result = this.getBlock() }
 
     CatchClause getCatch(int index) { result = this.getCatchClause(index) }
 

java/ql/lib/semmle/code/java/ControlFlowGraph.qll

@@ -117,7 +117,7 @@ private module Ast implements AstSig<Location> {
   final private class FinalTryStmt = J::TryStmt;
 
   class TryStmt extends FinalTryStmt {
-    Stmt getBody(int index) {
+    AstNode getBody(int index) {
       result = super.getResource(index)
       or
       index = count(super.getAResource()) and

shared/controlflow/codeql/controlflow/ControlFlowGraph.qll

@@ -190,7 +190,7 @@ signature module AstSig<LocationSig Location> {
      * position `index`. In some languages, there is only ever a single body
      * (with `index` 0).
      */
-    Stmt getBody(int index);
+    AstNode getBody(int index);
 
     /**
      * Gets the `catch` clause at the specified (zero-based) position `index`