Re-enable bed temperature automatically for transitory errors

Firmware/temperature.cpp

@@ -1738,6 +1738,11 @@ void handle_temp_error()
             temp_error_state.v = 0;
             WRITE(BEEPER, LOW);
             menu_unset_block(MENU_BLOCK_THERMAL_ERROR);
+
+            // hotend error was transitory and disappeared, re-enable bed
+            if (!target_temperature_bed)
+                target_temperature_bed = saved_bed_temperature;
+
             SERIAL_ECHOLNPGM("TM: error cleared");
         }
         break;