fix(p2ms): fix signature validation bypass due to operator precedence

src/cjs/payments/p2ms.cjs

@@ -90,7 +90,7 @@ function p2ms(a, opts) {
   function isAcceptableSignature(x) {
     return (
       bscript.isCanonicalScriptSignature(x) ||
-      (opts.allowIncomplete && x === OPS.OP_0) !== undefined
+      !!(opts.allowIncomplete && x === OPS.OP_0)
     );
   }
   v.parse(

src/esm/payments/p2ms.js

@@ -43,7 +43,7 @@ export function p2ms(a, opts) {
   function isAcceptableSignature(x) {
     return (
       bscript.isCanonicalScriptSignature(x) ||
-      (opts.allowIncomplete && x === OPS.OP_0) !== undefined
+      !!(opts.allowIncomplete && x === OPS.OP_0)
     );
   }
   v.parse(

test/fixtures/p2ms.json

@@ -407,6 +407,17 @@
         "input": "OP_0 ffffffffffffffff"
       }
     },
+    {
+      "description": "Invalid signature rejected even with allowIncomplete",
+      "exception": "Input has invalid signature\\(s\\)",
+      "options": {
+        "allowIncomplete": true
+      },
+      "arguments": {
+        "output": "OP_1 030000000000000000000000000000000000000000000000000000000000000001 OP_1 OP_CHECKMULTISIG",
+        "input": "OP_0 ffffffffffffffff"
+      }
+    },
     {
       "description": "n > 20 (2-of-21 multisig)",
       "exception": "Output is invalid",

ts_src/payments/p2ms.ts

@@ -47,7 +47,7 @@ export function p2ms(a: Payment, opts?: PaymentOpts): Payment {
   function isAcceptableSignature(x: Uint8Array | number): boolean {
     return (
       bscript.isCanonicalScriptSignature(x as Uint8Array) ||
-      (opts!.allowIncomplete && (x as number) === OPS.OP_0) !== undefined
+      !!(opts!.allowIncomplete && (x as number) === OPS.OP_0)
     );
   }