Block Bindings: Fix showing bindings field values in theme templates (#…

…65639)

* Move `is_custom` check to page case

* Check themeSlug in conditional

* Use `post.slug` directly

Co-authored-by: SantosGuillamot <santosguillamot@git.wordpress.org>
Co-authored-by: cbravobernal <cbravobernal@git.wordpress.org>

packages/editor/src/components/provider/index.js

@@ -188,26 +188,19 @@ export const ExperimentalEditorProvider = withRegistryProvider(
 			const postContext = {};
 			// If it is a template, try to inherit the post type from the slug.
 			if ( post.type === 'wp_template' ) {
-				if ( ! post.is_custom ) {
-					const [ kind ] = post.slug.split( '-' );
-					switch ( kind ) {
-						case 'page':
-							postContext.postType = 'page';
-							break;
-						case 'single':
-							// Infer the post type from the slug.
-							const postTypesSlugs =
-								postTypes?.map( ( entity ) => entity.slug ) ||
-								[];
-							const match = post.slug.match(
-								`^single-(${ postTypesSlugs.join(
-									'|'
-								) })(?:-.+)?$`
-							);
-							if ( match ) {
-								postContext.postType = match[ 1 ];
-							}
-							break;
+				if ( post.slug === 'page' ) {
+					postContext.postType = 'page';
+				} else if ( post.slug === 'single' ) {
+					postContext.postType = 'post';
+				} else if ( post.slug.split( '-' )[ 0 ] === 'single' ) {
+					// If the slug is single-{postType}, infer the post type from the slug.
+					const postTypesSlugs =
+						postTypes?.map( ( entity ) => entity.slug ) || [];
+					const match = post.slug.match(
+						`^single-(${ postTypesSlugs.join( '|' ) })(?:-.+)?$`
+					);
+					if ( match ) {
+						postContext.postType = match[ 1 ];
 					}
 				}
 			} else if (