Slider slide with no image renders broken <img> + leaks PHP warning, breaks mobile header #63

Summary

A homepage slider slide that has text (title/description) but no image renders a broken <img> tag with a raw PHP warning leaked into its width/height HTML attributes. On mobile, when this is the visible slide, the slider container collapses in height and its caption overlaps the mobile menu toggle button.

Steps to Reproduce

1. Customizer → Slider → configure a slide with a title and description but no image (e.g. Slide WooCommerce compatible. #4).
2. Publish and load the homepage.
3. Inspect the rendered <img> for that slide.
4. Additionally, resize the viewport to a mobile width (375px) and reload while this slide is the first/active one shown.

Expected Result

A slide without an image should render gracefully — either omit the <img> tag or use a safe fallback — with no PHP errors reaching the HTML output, and the mobile header should remain usable regardless of which slide is active.

Actual Result

• The <img> tag renders with src="", and its width/height attributes contain a literal PHP warning:

  <img width="<br /><b>Warning</b>:  Trying to access array offset on value of type bool in .../wp-content/themes/accelerate/inc/header-functions.php on line 94<br />" height="..." src="">

• On mobile (375px), with this image-less slide active, #featured-slider collapses to ~20px tall, and the slide's .entry-container caption (absolutely positioned) renders on top of the .menu-toggle button, producing an overlapping, illegible mobile header. Confirmed via bounding-rect inspection: caption top=269/bottom=316.5 vs. menu-toggle top=255/bottom=298.5.

Root Cause

inc/header-functions.php, function accelerate_featured_image_slider():

$attachment_post_id = attachment_url_to_postid( $accelerate_slider_image ); // 0 when no image
$image_value         = wp_get_attachment_image_src( $attachment_post_id, 'full' ); // returns false
...
<img width="<?php echo esc_attr( $image_value[1] ); ?>" height="<?php echo esc_attr( $image_value[2] ); ?>" ... src="<?php echo esc_url( $accelerate_slider_image ); ?>">

wp_get_attachment_image_src() returns false (not an array) when there's no valid attachment, so $image_value[1] / $image_value[2] trigger "Trying to access array offset on value of type bool" — which, with display_errors on, gets injected straight into the HTML attributes. The resulting zero-content image also has no defined height, which is what collapses the mobile slider container and lets the caption overlap the menu toggle.

Suggested Fix

Check that $image_value is a valid array (i.e. the slide actually has an image) before using it — and skip rendering the <img> (or figure) entirely when there is no image, rather than emitting a broken tag. Also worth giving #featured-slider/.slider-rotate a sane minimum height so a caption never overlaps site chrome above it.

Evidence

• img.getAttribute('width') / getAttribute('height') returned the raw warning text, captured via live browser testing.
• Mobile screenshot showing the "Menu" toggle visually overlapped by the slide caption with a broken-image icon.

Environment

• Accelerate 1.5.4, WordPress 7.1, PHP with display_errors on (warning leak is masked but the underlying bug exists regardless of that setting)
• Reproduced at desktop 1440×900 and mobile 375×812