TypeError: Cannot read properties of undefined (reading 'startsWith')

[jcubic]

I'm trying to compile LIPS Scheme CLI, pre compiled to commonJS with tsup (the project is not TypeScript, but esbuilt was throwing an error about one require).

Got this error:

TypeError: Cannot read properties of undefined (reading 'startsWith')
    at removeBrackets (file:///home/kuba/.config/nvm/versions/node/v20.6.1/lib/node_modules/porffor/compiler/2c.js:172:13)
    at cify (file:///home/kuba/.config/nvm/versions/node/v20.6.1/lib/node_modules/porffor/compiler/2c.js:743:78)
    at cify (file:///home/kuba/.config/nvm/versions/node/v20.6.1/lib/node_modules/porffor/compiler/2c.js:681:15)
    at cify (file:///home/kuba/.config/nvm/versions/node/v20.6.1/lib/node_modules/porffor/compiler/2c.js:681:15)
    at cify (file:///home/kuba/.config/nvm/versions/node/v20.6.1/lib/node_modules/porffor/compiler/2c.js:681:15)
    at cify (file:///home/kuba/.config/nvm/versions/node/v20.6.1/lib/node_modules/porffor/compiler/2c.js:681:15)
    at cify (file:///home/kuba/.config/nvm/versions/node/v20.6.1/lib/node_modules/porffor/compiler/2c.js:681:15)
    at default (file:///home/kuba/.config/nvm/versions/node/v20.6.1/lib/node_modules/porffor/compiler/2c.js:897:3)
    at default (file:///home/kuba/.config/nvm/versions/node/v20.6.1/lib/node_modules/porffor/compiler/index.js:258:15)
    at default (file:///home/kuba/.config/nvm/versions/node/v20.6.1/lib/node_modules/porffor/compiler/wrap.js:360:102)

To reproduce:

git clone https://github.com/jcubic/lips
cd lips
npm install
npm install tsup typescript
npx tsup bin/lips.js --format cjs
porf native -d dist/lips.cjs lips

This is the source from above stack trace:

/* 165 */ const removeBrackets = str => {
/* 166 */   // return str;
/* 167 */   // if (str.startsWith('(i32)(u32)')) return '(i32)(u32)(' + removeBrackets(str.slice(22, -1)) + ')';
/* 168 */ 
/* 169 */   for (const x in CValtype) {
/* 170 */     const p = `(${x})`;
/* 171 */     // if (str.startsWith(p)) return p + removeBrackets(str.slice(p.length));
/* 172 */     if (str.startsWith(p)) return str;
/* 173 */   }
/* ... */
/* 741 */         case Opcodes.br: {
/* 742 */           const ret = rets[brDepth - i[1] - 1];
/* 743 */           if (ret !== Blocktype.void) line(`_r${brs[brDepth - i[1] - 1]} = ${removeBrackets(vals.pop())}`);
/* 744 */           line(`goto j${brs[brDepth - i[1] - 1]}`);
/* 745 */ 
/* 746 */           break;
/* 747 */         }

vals.pop() is undefined.