Components returning empty string or new line are triggering malformed html error in liveview

[mhanberg]

Describe the bug

Reported by @evnp

#2

The second issue seems to relate to temple do blocks which may return nothing. I have this simple component, which worked fine on my previous version of Temple (0.14.0):

    defp unread_message_counter(assigns) do
      temple do
        if @count > 0 do
          span class: "flex items-center justify-center
                       bg-blue-500 rounded-full font-medium h-5 px-2ml-auto
                       text-xs text-white"
          do
            @count
          end
        end
      end
    end

Rendering this component with this branch installed leads to this error:

If I update to this, it works fine, so maybe this one is WAI and I should avoid returning nothing from temple blocks.

    defp unread_message_counter(assigns) do
      temple do
        if @count > 0 do
          span class: "flex items-center justify-center
                       bg-blue-500 rounded-full font-medium h-5 px-2ml-auto
                       text-xs text-white"
          do
            @count
          end
+++     else
+++       span
        end
      end
    end

[evnp]

Thanks for opening – just to add a bit more context (which I should have thought to try in the first place), it looks like returning any string directly from a temple block triggers the issue:

          end
+++     else
+++       "TEST"
        end

Wrapping the string in any Temple/HTML tag resolves the issue.

Verified the above works ok (without wrapping tag) on Temple v0.14.0.