Use resolved path when trying to load sheet content.

Also, if it can't be loaded then at least initialize it so that we
don't crash later (trying to access a NULL screen).

Fixes: lp:1841801
* https://bugs.launchpad.net/kicad/+bug/1841801

eeschema/tools/sch_editor_control.cpp

@@ -1051,7 +1051,8 @@ int SCH_EDITOR_CONTROL::Paste( const TOOL_EVENT& aEvent )
             }
             else
             {
-                m_frame->LoadSheetFromFile( sheet, g_CurrentSheet, sheet->GetFileName() );
+                if( !m_frame->LoadSheetFromFile( sheet, g_CurrentSheet, fn.GetFullPath() ) )
+                    m_frame->InitSheet( sheet, sheet->GetFileName() );
             }
         }