Add bad exists interpreter error fixtures

wasm-port/tests/wasm/node/verify_interp_wasm.mjs

@@ -1272,6 +1272,55 @@ verifyExpectedOutput(
 );
 
 for (const badFixture of [
+  {
+    name: "exists_1",
+    file: "exists-1.ngc",
+    readCount: 2,
+    executeCount: 1,
+    errorText: "Expected # reading parameter",
+  },
+  {
+    name: "exists_2",
+    file: "exists-2.ngc",
+    readCount: 2,
+    executeCount: 1,
+    errorText: "Expected ] reading bracketed parameter",
+  },
+  {
+    name: "exists_3",
+    file: "exists-3.ngc",
+    readCount: 3,
+    executeCount: 2,
+    errorText: "Parameter number out of range",
+  },
+  {
+    name: "exists_4",
+    file: "exists-4.ngc",
+    readCount: 2,
+    executeCount: 1,
+    errorText: "Unknown word starting with f",
+  },
+  {
+    name: "exists_5",
+    file: "exists-5.ngc",
+    readCount: 2,
+    executeCount: 1,
+    errorText: "Named parameter not terminated",
+  },
+  {
+    name: "exists_6",
+    file: "exists-6.ngc",
+    readCount: 2,
+    executeCount: 1,
+    errorText: "bad number format (conversion failed) parsing ''",
+  },
+  {
+    name: "exists_7",
+    file: "exists-7.ngc",
+    readCount: 2,
+    executeCount: 1,
+    errorText: "Expected ] reading bracketed parameter",
+  },
   {
     name: "nested",
     file: "nested.ngc",