fix #105 - validate all strings (#117)

any string that is not empty, including whitespace strings, should
validate?

Author: acao

.changeset/few-emus-live.md

@@ -0,0 +1,5 @@
+---
+"codemirror-json-schema": patch
+---
+
+validate all strings with length > 1

src/features/validation.ts

@@ -128,7 +128,7 @@ export class JSONValidation {
     const text = view.state.doc.toString();
 
     // ignore blank json strings
-    if (!text || text.trim().length < 3) return [];
+    if (!text || !text.length) return [];
 
     const json = this.parser(view.state);