3 files changed, 29 insertions, 6 deletions
diff --git a/src/js/_codegen/builtin-parser.ts b/src/js/_codegen/builtin-parser.ts
index ffd5671c1..4e35f13dd 100644
--- a/src/js/_codegen/builtin-parser.ts
+++ b/src/js/_codegen/builtin-parser.ts
@@ -79,12 +79,14 @@ export function sliceSourceCode(
       i = 1;
     } else if (endOnComma && contents.startsWith(",")) {
       if (bracketCount <= 1) {
-        result += ",";
         contents = contents.slice(1);
-        // if the next non-whitespace character is ), also consume
+        // if the next non-whitespace character is ), we will treat it like a )
         let match = contents.match(/^\s*\)/);
         if (match) {
           contents = contents.slice(match[0].length);
+          result += ")";
+        } else {
+          result += ",";
         }
         break;
       }
diff --git a/src/js/_codegen/client-js.ts b/src/js/_codegen/client-js.ts
index 2db3305fa..bd9ed63f4 100644
--- a/src/js/_codegen/client-js.ts
+++ b/src/js/_codegen/client-js.ts
@@ -27,10 +27,18 @@ export function createAssertClientJS(publicName: string) {
   return `
 let $assert = function(check, sourceString, ...message) {
   if (!check) {
-    console.error('[${publicName}] ASSERTION FAILED: ' + sourceString);
-    if(message.length)console.warn (' ${" ".repeat(publicName.length)}', ...message);
+    const prevPrepareStackTrace = Error.prepareStackTrace;
+    Error.prepareStackTrace = (e, stack) => {
+      return e.name + ': ' + e.message + '\\n' + stack.slice(1).map(x => '  at ' + x.toString()).join('\\n');
+    };
     const e = new Error(sourceString);
+    e.stack; // materialize stack
     e.name = 'AssertionError';
+    Error.prepareStackTrace = prevPrepareStackTrace;
+    console.error('[${publicName}] ASSERTION FAILED: ' + sourceString);
+    if (message.length) console.warn(...message);
+    console.warn(e.stack.split('\\n')[1] + '\\n');
+    if (Bun.env.ASSERT === 'CRASH') process.exit(0xAA);
     throw e;
   }
 }
diff --git a/src/js/_codegen/replacements.ts b/src/js/_codegen/replacements.ts
index 5ce646ad5..45f2426b5 100644
--- a/src/js/_codegen/replacements.ts
+++ b/src/js/_codegen/replacements.ts
@@ -141,14 +141,27 @@ export function applyReplacements(src: string, length: number) {
       ];
     } else if (name === "assert") {
       const checkSlice = sliceSourceCode(rest, true, undefined, true);
+      let rest2 = checkSlice.rest;
+      let extraArgs = "";
+      if (checkSlice.result.at(-1) === ",") {
+        const sliced = sliceSourceCode("(" + rest2.slice(1), true, undefined, false);
+        extraArgs = ", " + sliced.result.slice(1, -1);
+        rest2 = sliced.rest;
+      }
       return [
         slice.slice(0, match.index) +
           "(IS_BUN_DEVELOPMENT?$assert(" +
           checkSlice.result.slice(1, -1) +
           "," +
-          JSON.stringify(checkSlice.result.slice(1, -1).replace(/__intrinsic__/g, "$")) +
+          JSON.stringify(
+            checkSlice.result
+              .slice(1, -1)
+              .replace(/__intrinsic__/g, "$")
+              .trim(),
+          ) +
+          extraArgs +
           "):void 0)",
-        checkSlice.rest,
+        rest2,
         true,
       ];
     }