Updated the files.

my-app/node_modules/@webassemblyjs/utf8/src/decoder.js

@@ -0,0 +1,67 @@
+function con(b) {
+  if ((b & 0xc0) === 0x80) {
+    return b & 0x3f;
+  } else {
+    throw new Error("invalid UTF-8 encoding");
+  }
+}
+
+function code(min, n) {
+  if (n < min || (0xd800 <= n && n < 0xe000) || n >= 0x10000) {
+    throw new Error("invalid UTF-8 encoding");
+  } else {
+    return n;
+  }
+}
+
+export function decode(bytes) {
+  return _decode(bytes)
+    .map((x) => String.fromCharCode(x))
+    .join("");
+}
+
+function _decode(bytes) {
+  const result = [];
+  while (bytes.length > 0) {
+    const b1 = bytes[0];
+    if (b1 < 0x80) {
+      result.push(code(0x0, b1));
+      bytes = bytes.slice(1);
+      continue;
+    }
+
+    if (b1 < 0xc0) {
+      throw new Error("invalid UTF-8 encoding");
+    }
+
+    const b2 = bytes[1];
+    if (b1 < 0xe0) {
+      result.push(code(0x80, ((b1 & 0x1f) << 6) + con(b2)));
+      bytes = bytes.slice(2);
+      continue;
+    }
+
+    const b3 = bytes[2];
+    if (b1 < 0xf0) {
+      result.push(code(0x800, ((b1 & 0x0f) << 12) + (con(b2) << 6) + con(b3)));
+      bytes = bytes.slice(3);
+      continue;
+    }
+
+    const b4 = bytes[3];
+    if (b1 < 0xf8) {
+      result.push(
+        code(
+          0x10000,
+          ((((b1 & 0x07) << 18) + con(b2)) << 12) + (con(b3) << 6) + con(b4)
+        )
+      );
+      bytes = bytes.slice(4);
+      continue;
+    }
+
+    throw new Error("invalid UTF-8 encoding");
+  }
+
+  return result;
+}

my-app/node_modules/@webassemblyjs/utf8/src/encoder.js

@@ -0,0 +1,44 @@
+function con(n) {
+  return 0x80 | (n & 0x3f);
+}
+
+export function encode(str) {
+  const arr = str.split("").map((x) => x.charCodeAt(0));
+  return _encode(arr);
+}
+
+function _encode(arr) {
+  if (arr.length === 0) {
+    return [];
+  }
+
+  const [n, ...ns] = arr;
+
+  if (n < 0) {
+    throw new Error("utf8");
+  }
+
+  if (n < 0x80) {
+    return [n, ..._encode(ns)];
+  }
+
+  if (n < 0x800) {
+    return [0xc0 | (n >>> 6), con(n), ..._encode(ns)];
+  }
+
+  if (n < 0x10000) {
+    return [0xe0 | (n >>> 12), con(n >>> 6), con(n), ..._encode(ns)];
+  }
+
+  if (n < 0x110000) {
+    return [
+      0xf0 | (n >>> 18),
+      con(n >>> 12),
+      con(n >>> 6),
+      con(n),
+      ..._encode(ns),
+    ];
+  }
+
+  throw new Error("utf8");
+}

my-app/node_modules/@webassemblyjs/utf8/src/index.js

@@ -0,0 +1,4 @@
+// @flow
+
+export { decode } from "./decoder";
+export { encode } from "./encoder";