Merge pull request The-OpenROAD-Project#9531 from The-OpenROAD-Project-staging/gui-mm-crash

gui: Set default scene to prevent null deref

Author: maliberty

src/gui/src/staGuiInterface.cpp

@@ -976,7 +976,7 @@ void PathGroupSlackEndVisitor::resetWorstSlack()
 
 STAGuiInterface::STAGuiInterface(sta::dbSta* sta)
     : sta_(sta),
-      scene_(nullptr),
+      scene_(sta ? sta->cmdScene() : nullptr),
       use_max_(true),
       one_path_per_endpoint_(true),
       max_path_count_(50),

src/gui/src/staGuiInterface.h

@@ -326,7 +326,11 @@ class STAGuiInterface
  public:
   STAGuiInterface(sta::dbSta* sta = nullptr);
 
-  void setSTA(sta::dbSta* sta) { sta_ = sta; }
+  void setSTA(sta::dbSta* sta)
+  {
+    sta_ = sta;
+    scene_ = sta->cmdScene();
+  }
   sta::dbSta* getSTA() const { return sta_; }
 
   sta::dbNetwork* getNetwork() const { return sta_->getDbNetwork(); }