Fix memory leak in non-constant module declaration

parser.y

@@ -298,6 +298,7 @@ Module:
   if (!block_is_const($2)) {
     FAIL(@$, "Module metadata must be constant");
     $$ = gen_noop();
+    block_free($2);
   } else {
     $$ = gen_module($2);
   }

tests/jq.test

@@ -1181,6 +1181,10 @@ include "c"; [a, c]
 null
 [0,"acmehbah"]
 
+%%FAIL
+module (.+1); 0
+jq: error: Module metadata must be constant at <top-level>, line 1:
+
 %%FAIL
 include "a" (.+1); 0
 jq: error: Module metadata must be constant at <top-level>, line 1: