Error message on use of plugin

I noticed after testing out the Image Hover Effects block that the following error message showed up:

Warning: Illegal string offset ‘items’ in /Users/paaljoachimromdahl/Sites/mag.dev.cc/wp-content/plugins/image-hover-effects-block/image-hover-effects-block.php on line 413
Call Stack
# Time Memory Function Location
1 0.0031 579224 {main}( ) …/index.php:0
2 0.0032 581936 require( ‘/Users/paaljoachimromdahl/Sites/mag.dev.cc/wp-blog-header.php’ ) …/index.php:17
3 0.2500 31276704 require_once( ‘/Users/paaljoachimromdahl/Sites/mag.dev.cc/wp-includes/template-loader.php’ ) …/wp-blog-header.php:19
4 0.2524 31380432 include( ‘/Users/paaljoachimromdahl/Sites/mag.dev.cc/wp-content/themes/gridd/page.php’ ) …/template-loader.php:98
5 0.3314 31779104 Gridd\Theme::get_template_part( ) …/page.php:22
6 0.3314 31779104 get_template_part( ) …/Theme.php:367
7 0.3314 31779672 locate_template( ) …/general-template.php:168
8 0.3315 31779800 load_template( ) …/template.php:671
9 0.3315 31782296 require( ‘/Users/paaljoachimromdahl/Sites/mag.dev.cc/wp-content/themes/gridd/template-parts/content-page.php’ ) …/template.php:724
10 0.3324 31784768 Gridd\Theme::get_template_part( ) …/content-page.php:17
11 0.3324 31784768 get_template_part( ) …/Theme.php:367
12 0.3325 31785368 locate_template( ) …/general-template.php:168
13 0.3325 31785496 load_template( ) …/template.php:671
14 0.3326 31787088 require( ‘/Users/paaljoachimromdahl/Sites/mag.dev.cc/wp-content/themes/gridd/template-parts/part-post-content.php’ ) …/template.php:724
15 0.3326 31787088 Gridd\Theme::get_template_part( ) …/part-post-content.php:12
16 0.3326 31787088 get_template_part( ) …/Theme.php:367
17 0.3326 31787664 locate_template( ) …/general-template.php:168
18 0.3327 31787792 load_template( ) …/template.php:671
19 0.3329 31792096 require( ‘/Users/paaljoachimromdahl/Sites/mag.dev.cc/wp-content/themes/gridd/template-parts/the-content.php’ ) …/template.php:724
20 0.3329 31792096 the_content( ) …/the-content.php:25
21 0.3331 31792440 apply_filters( ) …/post-template.php:253
22 0.3331 31792840 WP_Hook->apply_filters( ) …/plugin.php:206
23 0.3338 31794552 do_blocks( ) …/class-wp-hook.php:288
24 0.3373 31912992 render_block( ) …/blocks.php:537
25 0.3373 31912992 apply_filters( ) …/blocks.php:455
26 0.3373 31913392 WP_Hook->apply_filters( ) …/plugin.php:206
27 0.3373 31914144 gutenberg_provide_render_callback_with_block_object( ) …/class-wp-hook.php:288
28 0.3373 31914304 render_block( ) …/compat.php:59
29 0.3373 31914304 apply_filters( ) …/blocks.php:455
30 0.3373 31914704 WP_Hook->apply_filters( ) …/plugin.php:206
31 0.3373 31915456 gutenberg_provide_render_callback_with_block_object( ) …/class-wp-hook.php:288
32 0.3374 31915904 render_block( ) …/compat.php:59
33 0.3374 31915904 apply_filters( ) …/blocks.php:455
34 0.3374 31916304 WP_Hook->apply_filters( ) …/plugin.php:206
35 0.3374 31917056 gutenberg_provide_render_callback_with_block_object( ) …/class-wp-hook.php:288
36 0.3375 31919672 ImageHoverEffectsBlock->iheg_render_callback( ) …/compat.php:70

( ! ) Warning: Invalid argument supplied for foreach() in /Users/paaljoachimromdahl/Sites/mag.dev.cc/wp-content/plugins/image-hover-effects-block/image-hover-effects-block.php on line 413
Call Stack
# Time Memory Function Location
1 0.0031 579224 {main}( ) …/index.php:0
2 0.0032 581936 require( ‘/Users/paaljoachimromdahl/Sites/mag.dev.cc/wp-blog-header.php’ ) …/index.php:17
3 0.2500 31276704 require_once( ‘/Users/paaljoachimromdahl/Sites/mag.dev.cc/wp-includes/template-loader.php’ ) …/wp-blog-header.php:19
4 0.2524 31380432 include( ‘/Users/paaljoachimromdahl/Sites/mag.dev.cc/wp-content/themes/gridd/page.php’ ) …/template-loader.php:98
5 0.3314 31779104 Gridd\Theme::get_template_part( ) …/page.php:22
6 0.3314 31779104 get_template_part( ) …/Theme.php:367
7 0.3314 31779672 locate_template( ) …/general-template.php:168
8 0.3315 31779800 load_template( ) …/template.php:671
9 0.3315 31782296 require( ‘/Users/paaljoachimromdahl/Sites/mag.dev.cc/wp-content/themes/gridd/template-parts/content-page.php’ ) …/template.php:724
10 0.3324 31784768 Gridd\Theme::get_template_part( ) …/content-page.php:17
11 0.3324 31784768 get_template_part( ) …/Theme.php:367
12 0.3325 31785368 locate_template( ) …/general-template.php:168
13 0.3325 31785496 load_template( ) …/template.php:671
14 0.3326 31787088 require( ‘/Users/paaljoachimromdahl/Sites/mag.dev.cc/wp-content/themes/gridd/template-parts/part-post-content.php’ ) …/template.php:724
15 0.3326 31787088 Gridd\Theme::get_template_part( ) …/part-post-content.php:12
16 0.3326 31787088 get_template_part( ) …/Theme.php:367
17 0.3326 31787664 locate_template( ) …/general-template.php:168
18 0.3327 31787792 load_template( ) …/template.php:671
19 0.3329 31792096 require( ‘/Users/paaljoachimromdahl/Sites/mag.dev.cc/wp-content/themes/gridd/template-parts/the-content.php’ ) …/template.php:724
20 0.3329 31792096 the_content( ) …/the-content.php:25
21 0.3331 31792440 apply_filters( ) …/post-template.php:253
22 0.3331 31792840 WP_Hook->apply_filters( ) …/plugin.php:206
23 0.3338 31794552 do_blocks( ) …/class-wp-hook.php:288
24 0.3373 31912992 render_block( ) …/blocks.php:537
25 0.3373 31912992 apply_filters( ) …/blocks.php:455
26 0.3373 31913392 WP_Hook->apply_filters( ) …/plugin.php:206
27 0.3373 31914144 gutenberg_provide_render_callback_with_block_object( ) …/class-wp-hook.php:288
28 0.3373 31914304 render_block( ) …/compat.php:59
29 0.3373 31914304 apply_filters( ) …/blocks.php:455
30 0.3373 31914704 WP_Hook->apply_filters( ) …/plugin.php:206
31 0.3373 31915456 gutenberg_provide_render_callback_with_block_object( ) …/class-wp-hook.php:288
32 0.3374 31915904 render_block( ) …/compat.php:59
33 0.3374 31915904 apply_filters( ) …/blocks.php:455
34 0.3374 31916304 WP_Hook->apply_filters( ) …/plugin.php:206
35 0.3374 31917056 gutenberg_provide_render_callback_with_block_object( ) …/class-wp-hook.php:288
36 0.3375 31919672 ImageHoverEffectsBlock->iheg_render_callback( )