How to deal with unavailable sensors braking frontend?

This is a Challenge I have had for as long as I have run Home-Assistant, sensors going offline/unavailable or something like that, and then braking the UI.
I have examples.
My question is, how should I deal with these kind of errors on a general basis whiteout making my code unnecessarily long and complicated? I guess a “if x, else y” for every sensor is one way, but it is making it all more complex.

Example:

{% if is_state("binary_sensor.syncthing_http_response_status", "off") -%}✔️ HTTP Response OK{%- else -%}❌ HTTP Response FAIL{%- endif %}


JOBB-PC
remote State: {{ state_attr("sensor.syncthing_unraid_jobb_pc", "remoteState") }}
Completion: {{ state_attr("sensor.syncthing_unraid_jobb_pc", "completion") }}%
Global items: {{ state_attr("sensor.syncthing_unraid_jobb_pc", "globalItems") }} / {{ ( state_attr("sensor.syncthing_unraid_jobb_pc", "globalBytes") / (1024*1024*1024) ) | round(2) }} GB

KONTOR-PC
remote State: {{ state_attr("sensor.syncthing_unraid_kontor_pc", "remoteState") }}
Completion: {{ state_attr("sensor.syncthing_unraid_kontor_pc", "completion") }}%
Global items: {{ state_attr("sensor.syncthing_unraid_kontor_pc", "globalItems") }} / {{ ( state_attr("sensor.syncthing_unraid_kontor_pc", "globalBytes") / (1024*1024*1024) ) | round(2) }} GB

FLEMMING-LAPTOP
remote State: {{ state_attr("sensor.syncthing_unraid_flemming_laptop", "remoteState") }}
Completion: {{ state_attr("sensor.syncthing_unraid_flemming_laptop", "completion") }}%
Global items: {{ state_attr("sensor.syncthing_unraid_flemming_laptop", "globalItems") }} / {{ ( state_attr("sensor.syncthing_unraid_flemming_laptop", "globalBytes") / (1024*1024*1024) ) | round(2) }} GB

FLEMMING-TLF
remote State: {{ state_attr("sensor.syncthing_unraid_flemming_tlf", "remoteState") }}
Completion: {{ state_attr("sensor.syncthing_unraid_flemming_tlf", "completion") }}%
Global items: {{ state_attr("sensor.syncthing_unraid_flemming_tlf", "globalItems") }} / {{ ( state_attr("sensor.syncthing_unraid_flemming_tlf", "globalBytes") / (1024*1024*1024) ) | round(2) }} GB

One more:
image

type: custom:vertical-stack-in-card
horizontal: true
cards:
  - type: custom:mushroom-template-card
    primary: Kaffetrakter
    secondary: |+
      {% if is_state('switch.zwave_6_switch', 'on') %}På{% else %}Av{% endif %}
      {{ states("sensor.zwave_6_electric1_w_meter_66049_value")| round(0) }}W

    icon: mdi:coffee-maker
    multiline_secondary: true
    tap_action:
      action: none
    hold_action:
      action: none
    double_tap_action:
      action: none
    icon_color: >-
      {% if is_state('switch.zwave_6_switch', 'on') %} yellow {% else %}{% endif
      %}
  - type: vertical-stack
    cards:
      - type: horizontal-stack
        cards:
          - type: vertical-stack
            cards:
              - type: custom:mushroom-chips-card
                chips:
                  - type: conditional
                    conditions:
                      - entity: switch.zwave_6_switch
                        state: 'off'
                    chip:
                      type: template
                      double_tap_action:
                        action: none
                      content: Slå på
                      tap_action:
                        action: call-service
                        service: switch.turn_on
                        data: {}
                        target:
                          entity_id: switch.zwave_6_switch
                      hold_action:
                        action: none
                      icon_color: green
                      icon: mdi:power-on
                  - type: conditional
                    conditions:
                      - entity: switch.zwave_6_switch
                        state: 'on'
                    chip:
                      type: template
                      double_tap_action:
                        action: none
                      content: Slå av
                      tap_action:
                        action: call-service
                        service: switch.turn_off
                        data: {}
                        target:
                          entity_id: switch.zwave_6_switch
                      hold_action:
                        action: none
                      icon_color: red
                      icon: mdi:power-off
      - type: horizontal-stack
        cards:
          - type: custom:mushroom-chips-card
            chips:
              - type: conditional
                conditions:
                  - entity: switch.zwave_6_switch
                    state: 'on'
                chip:
                  type: template
                  double_tap_action:
                    action: none
                  icon: mdi:restart
                  content: Tilbakestill timer
                  tap_action:
                    action: call-service
                    service: timer.start
                    data: {}
                    target:
                      entity_id: timer.caffe_maker_countdown
                  hold_action:
                    action: none
                  icon_color: orange
          - type: conditional
            conditions:
              - entity: switch.zwave_6_switch
                state: 'on'
            card:
              type: custom:timer-bar-card
              name: ''
              icon: mdi:mdi-blank
              bar_width: null
              bar_height: null
              entity:
                - timer.caffe_maker_countdown

{% if has_value("sensor..... to show, hide codes when sensor is available or not.