FIX: only invoke fp-lib-table options editor when table not empty.

pcbnew/dialogs/dialog_fp_lib_table.cpp

@@ -583,6 +583,8 @@ private:
     {
         FP_TBL_MODEL*   tbl = cur_model();
 
+        if( tbl->GetNumberRows() )
+        {
             int     curRow = getCursorRow();
             ROW&    row    = tbl->rows[curRow];
 
@@ -607,6 +609,7 @@ private:
 #endif
             }
         }
+    }
 
     void onCancelButtonClick( wxCommandEvent& event )
     {