[Rust] Misc interaction::report improvements

- Add `Debug` impl to `ReportCollection`
- Fix flow graph related api's not being optional

Author: emesare

rust/src/interaction/report.rs

@@ -1,3 +1,4 @@
+use std::fmt::Debug;
 use std::ptr::NonNull;
 
 use binaryninjacore_sys::*;
@@ -68,9 +69,12 @@ impl ReportCollection {
         unsafe { BnString::into_string(raw) }
     }
 
-    fn flow_graph(&self, i: usize) -> Ref<FlowGraph> {
+    fn flow_graph(&self, i: usize) -> Option<Ref<FlowGraph>> {
         let raw = unsafe { BNGetReportFlowGraph(self.handle.as_ptr(), i) };
-        unsafe { FlowGraph::ref_from_raw(raw) }
+        match raw.is_null() {
+            false => Some(unsafe { FlowGraph::ref_from_raw(raw) }),
+            true => None,
+        }
     }
 
     pub fn add_text(&self, view: &BinaryView, title: &str, contents: &str) {
@@ -137,6 +141,14 @@ impl ReportCollection {
     }
 }
 
+impl Debug for ReportCollection {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        f.debug_struct("ReportCollection")
+            .field("count", &self.count())
+            .finish()
+    }
+}
+
 unsafe impl RefCountable for ReportCollection {
     unsafe fn inc_ref(handle: &Self) -> Ref<Self> {
         let raw = unsafe { BNNewReportCollectionReference(handle.handle.as_ptr()) };
@@ -237,7 +249,9 @@ pub struct ReportFlowGraph<'a>(ReportInner<'a>);
 
 impl ReportFlowGraph<'_> {
     pub fn flow_graph(&self) -> Ref<FlowGraph> {
-        self.0.flow_graph()
+        self.0
+            .flow_graph()
+            .expect("Flow graph not available for flow graph report!")
     }
 
     pub fn update_report_flow_graph(&self, graph: &FlowGraph) {
@@ -271,7 +285,7 @@ impl ReportInner<'_> {
         self.collection.plain_text(self.index)
     }
 
-    fn flow_graph(&self) -> Ref<FlowGraph> {
+    fn flow_graph(&self) -> Option<Ref<FlowGraph>> {
         self.collection.flow_graph(self.index)
     }