[spatialite] Don't crash with NULL geometries (Fix #8739)

Author: m-kuhn

src/analysis/openstreetmap/qgsosmdatabase.cpp

@@ -489,7 +489,10 @@ void QgsOSMDatabase::exportSpatiaLiteWays( bool closed, const QString& tableName
         sqlite3_bind_null( stmtInsert, ++col );
     }
 
-    sqlite3_bind_blob( stmtInsert, ++col, geom->asWkb(), ( int ) geom->wkbSize(), SQLITE_STATIC );
+    if ( geom )
+      sqlite3_bind_blob( stmtInsert, ++col, geom->asWkb(), ( int ) geom->wkbSize(), SQLITE_STATIC );
+    else
+      sqlite3_bind_null( stmtInsert, ++col );
 
     int insertRes = sqlite3_step( stmtInsert );
     if ( insertRes != SQLITE_DONE )