Sidebar featured images only on single post pages

After updating to WordPress 6.x and updating my theme (Clean Black based) and then merging the customizations back in with meld (yes, I really should do a child theme but this is a pretty simple theme so meld is fine), I didn’t really like the way the post thumbnails are shown, prefering to keep it to the right. I mean clean black was last updated in 2014 and while it still works fine, but that was a while ago. Plus I had hand-coded a theme sometime in the naughties and wanted to more or less keep it while taking advantage of some of the responsive features introduced about then.

Pretty much any question one might have, someone has asked it before, and I found some reasonable solutions, some more complex than others. There’s a reasonable 3 modification solution that works by creating another sidebar.php file (different name, same function) that gets called by single.php (and not the main page) that has the modification you want, but that seemed unnecessarily complicated. I settled on a conditional test is_singular which works to limit the get_the_post_thumbnail call to where I wanted and not to invoke it elsewhere. A few of the other options on the same stackexchange thread didn’t work for me, your install may be different. What I settled on (including a map call for geo-tagged posts) is:

      ID, 'thumbnail');
           echo GeoMashup::map('height=150&width=300&zoom=5&add_overview_control=false&add_map_type_control=false&add_map_control=false');
           } ?>

And I get what i was looking for, a graphical anchor at the top of the single post (but not pages) for the less purely lexically inclined that didn’t clutter the home page or other renderings with a wee bit o php.