Fix double call of OnPgmExit

Also fix bad filename being passed to pcbnew when starting
from a blank schematic in standalone mode

Fixes https://gitlab.com/kicad/code/kicad/-/issues/5786

common/single_top.cpp

@@ -161,13 +161,7 @@ struct APP_SINGLE_TOP : public wxApp
 
         try
         {
-            if( !program.OnPgmInit() )
-            {
-                program.OnPgmExit();
-                return false;
-            }
-
-            return true;
+            return program.OnPgmInit();
         }
         catch( const std::exception& e )
         {
@@ -294,7 +288,11 @@ bool PGM_SINGLE_TOP::OnPgmInit()
 #endif
 
     if( !InitPgm() )
+    {
+        // Clean up
+        OnPgmExit();
         return false;
+    }
 
 #if !defined(BUILD_KIWAY_DLL)
 
@@ -353,6 +351,8 @@ bool PGM_SINGLE_TOP::OnPgmInit()
         if( appType == FRAME_T_COUNT )
         {
             wxLogError( wxT( "Unknown frame: %s" ), frameName );
+            // Clean up
+            OnPgmExit();
             return false;
         }
     }

eeschema/sch_component.h

@@ -611,7 +611,7 @@ public:
 
     wxPoint GetPinPhysicalPosition( const LIB_PIN* Pin ) const;
 
-    bool IsConnectable() const override { return m_onBoard; }
+    bool IsConnectable() const override { return true; }
 
     bool CanConnect( const SCH_ITEM* aItem ) const override
     {

eeschema/sch_edit_frame.cpp

@@ -903,7 +903,7 @@ void SCH_EDIT_FRAME::OnOpenPcbnew( wxCommandEvent& event )
 {
     wxFileName kicad_board = Prj().AbsolutePath( Schematic().GetFileName() );
 
-    if( kicad_board.IsOk() )
+    if( kicad_board.IsOk() && !Schematic().GetFileName().IsEmpty() )
     {
         kicad_board.SetExt( PcbFileExtension );
         wxFileName legacy_board( kicad_board );
@@ -940,6 +940,8 @@ void SCH_EDIT_FRAME::OnOpenPcbnew( wxCommandEvent& event )
     }
     else
     {
+        // If we are running inside a project, it should be impossible for this case to happen
+        wxASSERT( Kiface().IsSingle() );
         ExecuteFile( this, PCBNEW_EXE );
     }
 }