Description: fix a problem where chunk gets undefined
Author: Julien Puydt
Forwarded: yes

--- a/src/MagicString.js
+++ b/src/MagicString.js
@@ -524,6 +524,7 @@
 		const searchForward = index > chunk.end;
 
 		while ( true ) {
+			if (!chunk) return undefined;
 			if ( chunk.contains( index ) ) return this._splitChunk( chunk, index );
 
 			chunk = searchForward ?