fix(pass-style)!: only well-formed strings are passable

Author: erights

packages/pass-style/src/passStyleOf.js

@@ -26,6 +26,28 @@ const { details: X, Fail, quote: q } = assert;
 const { ownKeys } = Reflect;
 const { isFrozen } = Object;
 
+// @ts-expect-error TS does not yet know about `isWellFormed`
+const hasWellFormedMethod = !!String.prototype.isWellFormed;
+
+const isWellFormed = hasWellFormedMethod
+  ? // @ts-expect-error TS does not yet know about `isWellFormed`
+    str => typeof str === 'string' && str.isWellFormed()
+  : str => {
+      if (typeof str !== 'string') {
+        return false;
+      }
+      for (const ch of str) {
+        const cp = /** @type {number} */ (ch.codePointAt(0));
+        if (cp >= 0xd800 && cp <= 0xdfff) {
+          return false;
+        }
+      }
+      return true;
+    };
+
+const assertWellFormed = str =>
+  isWellFormed(str) || Fail`Expected well-formed unicode string: ${str}`;
+
 /**
  * @param {PassStyleHelper[]} passStyleHelpers
  * @returns {Record<HelperPassStyle, PassStyleHelper> }
@@ -124,12 +146,15 @@ const makePassStyleOf = passStyleHelpers => {
       const typestr = typeof inner;
       switch (typestr) {
         case 'undefined':
-        case 'string':
         case 'boolean':
         case 'number':
         case 'bigint': {
           return typestr;
         }
+        case 'string': {
+          assertWellFormed(inner);
+          return 'string';
+        }
         case 'symbol': {
           assertPassableSymbol(inner);
           return 'symbol';