fix: update incorrect isScrollable constraints

PR-URL: #2293
Ref: #2149

Signed-off-by: Snehil Shah <snehilshah.989@gmail.com>
Reviewed-by: Philipp Burckhardt <pburckhardt@outlook.com>

Author: Snehil-Shah

lib/node_modules/@stdlib/repl/lib/output_stream.js

@@ -271,7 +271,7 @@ setNonEnumerableReadOnly( OutputStream.prototype, '_pagerHeight', function pager
 	if ( vh < MIN_VIEWPORT_HEIGHT ) {
 		return -1;
 	}
-	return vh - RESERVED_PAGING_ROWS;
+	return vh - RESERVED_PAGING_ROWS; // FIXME: reserved paging rows being a constant assumes that the input prompt spans just 1 row. This might not be the case with multi-line inputs triggering the pager as it will result in an incomplete UI with only the last line of the multi-line input visible in the pager view.
 });
 
 /**
@@ -285,8 +285,8 @@ setNonEnumerableReadOnly( OutputStream.prototype, '_pagerHeight', function pager
 * @returns {boolean} boolean indicating whether content is "scrollable"
 */
 setNonEnumerableReadOnly( OutputStream.prototype, '_isScrollable', function isScrollable( N ) {
-	var h = this._pagerHeight();
-	return ( h > 0 && N > h );
+	var vh = this._repl.viewportHeight();
+	return ( vh >= MIN_VIEWPORT_HEIGHT && N > vh - 2 ); // 2 rows reserved for the input and the next prompt
 });
 
 /**