Escape the literals that would merge with the syntax beside them

src/json-value.ts

@@ -1,10 +1,18 @@
 export type JsonValue = JsonValue[] | boolean | null | number | string | { [key: string]: JsonValue }
 
 export function isJsonValue(value: unknown): value is JsonValue {
-  if (value === null) return true
-  if (typeof value === 'boolean' || typeof value === 'string') return true
-  if (typeof value === 'number') return Number.isFinite(value)
-  if (Array.isArray(value)) return [...value].every(isJsonValue)
-  if (typeof value === 'object') return Object.values(value).every(isJsonValue)
-  return false
+  const pending: unknown[] = [value]
+  while (pending.length > 0) {
+    const item = pending.pop()
+    if (item === null || typeof item === 'boolean' || typeof item === 'string') continue
+    if (typeof item === 'number') {
+      if (!Number.isFinite(item)) return false
+      continue
+    }
+    // A hole is not a JSON value, and Array.prototype methods skip holes — spreading materialises them.
+    if (Array.isArray(item)) pending.push(...item)
+    else if (typeof item === 'object') pending.push(...Object.values(item))
+    else return false
+  }
+  return true
 }