l.warn -> l.debug for formatter warning (#151)

* l.warn -> l.debug for formatter

* Debug with function

* Fix console spy

packages/api-format/src/format.spec.js

@@ -12,7 +12,7 @@ describe('format', () => {
 
   beforeEach(() => {
     echoSpy = jest.fn(echo);
-    warnSpy = jest.spyOn(console, 'warn');
+    warnSpy = jest.spyOn(console, 'log');
 
     formatters = new Map([
       ['Address', echoSpy],

packages/api-format/src/format.ts

@@ -28,7 +28,7 @@ function formatSingleType (formatters: FormattersFunctionMap, type: Param$Types,
   const formatter = formatters.get(type);
 
   if (isUndefined(formatter)) {
-    l.warn(`Unable to find default formatter for '${typeToString(type)}', falling back to echo`);
+    l.debug(() => `Unable to find default formatter for '${typeToString(type)}', falling back to echo`);
 
     return echo(value);
   }