Incorrect use of _n() in new strings for 5.9

[tobifjellner]

The new code for WordPress contains three instances where the "Template Part"/"Template Parts" string pair is used.

However, this is usage of _n() is incorrect.
If you want to handle just the singular and plural terms, then this should be handled in the code (if 1 == n then ...) and not by using _n()

Alternatively, if these strings are used together with the relevant number, then a placeholder for the count variable should be present in the string (i.e. printf)

Three references (to the current as-built package)
​https://build.trac.wordpress.org/browser/trunk/wp-includes/js/dist/editor.js?marks=5220#L5220

const entityLabel = name === 'wp_template_part' ? Object(external_wp_i18n_["_n"])('Template Part', 'Template Parts', list.length) : entity.label; // Set description based on type of entity.

​https://build.trac.wordpress.org/browser/trunk/wp-includes/js/dist/block-library.js?marks=38830#L38830

​https://build.trac.wordpress.org/browser/trunk/wp-includes/js/dist/editor.js?marks=5220#L5220

[felipeelia]

Not exactly sure if this helps but the code seems to come from this line: ​https://github.com/WordPress/gutenberg/blob/trunk/packages/editor/src/components/entities-saved-states/entity-type-list.js#L54

[audrasjb]

Thanks @tobifjellner for spotting this!
Reported upstream on Gutenberg: ​https://github.com/WordPress/gutenberg/issues/37471

Moving to 5.9, waiting for an upstream resolution.

[ocean90]

Closing as reported-upstream after moving the issue to the WordPress 5.9 Must-Haves project.