refactor: add strict JSON parsing helpers

src/lnurlcash/jsonParsing.ts

@@ -0,0 +1,20 @@
+export const isJsonObject = (value: unknown): value is Record<string, unknown> =>
+  typeof value === 'object' && value !== null && !Array.isArray(value)
+
+export const parseJsonObject = (source: string): Record<string, unknown> => {
+  const parsed: unknown = JSON.parse(source)
+  if (!isJsonObject(parsed)) throw new TypeError('Expected a JSON object.')
+  return parsed
+}
+
+export const parseJsonArray = (source: string): unknown[] => {
+  const parsed: unknown = JSON.parse(source)
+  if (!Array.isArray(parsed)) throw new TypeError('Expected a JSON array.')
+  return Array.from(parsed, (value: unknown) => value)
+}
+
+export const parseJsonObjectArray = (source: string): Array<Record<string, unknown>> =>
+  parseJsonArray(source).map((value) => {
+    if (!isJsonObject(value)) throw new TypeError('Expected a JSON object array.')
+    return value
+  })