Don't consume the end pattern multiple times in script pattern

src/notcl.ts

@@ -1,5 +1,14 @@
 import { escapeHtml } from "./helpers";
-import { AtLeast, Choose, End, Pattern, Regex, Sequence, Use } from "./peg";
+import {
+  AtLeast,
+  Choose,
+  End,
+  Pattern,
+  Peek,
+  Regex,
+  Sequence,
+  Use,
+} from "./peg";
 import {
   Script,
   Word as WordType,
@@ -105,10 +114,12 @@ function scriptTmpl(bareWordCharRegex: RegExp, endPattern: Pattern<unknown>) {
       Choose(
         PreWordWhitespace.map(() => []),
         CommandTerminator.map(() => []),
-        Sequence(Comment, Choose(CommandTerminator, endPattern)).map(() => []),
+        Sequence(Comment, Choose(CommandTerminator, Peek(endPattern))).map(
+          () => []
+        ),
         Sequence(
           commandTmpl(bareWordCharRegex),
-          Choose(CommandTerminator, endPattern)
+          Choose(CommandTerminator, Peek(endPattern))
         ).map(([words]) => words)
       )
     ),

src/peg.ts

@@ -182,6 +182,16 @@ export function AtLeast<T>(min: number, pattern: Pattern<T>): Pattern<T[]> {
   }).expects(pattern.expectLabel);
 }
 
+/**
+ * Creates a pattern that matches the given pattern, but consumes no input.
+ */
+export function Peek<T>(pattern: Pattern<T>): Pattern<T> {
+  return WrapPattern(function (source, index) {
+    const [value, furthest, expected] = pattern(source, index);
+    return [value ? [value[0], index] : null, furthest, expected];
+  }).expects(pattern.expectLabel);
+}
+
 /**
  * Creates a pattern that matches the end of input
  */