error handling for classpath schema client

Author: rjruizes

core/src/main/java/org/everit/json/schema/loader/ClassPathAwareSchemaClient.java

@@ -4,7 +4,9 @@
 import static java.util.Collections.unmodifiableList;
 import static java.util.Objects.requireNonNull;
 
+import java.io.IOException;
 import java.io.InputStream;
+import java.io.UncheckedIOException;
 import java.util.List;
 import java.util.Optional;
 
@@ -19,9 +21,17 @@ class ClassPathAwareSchemaClient implements SchemaClient {
     }
 
     @Override public InputStream get(String url) {
-        return handleProtocol(url)
-                .map(this::loadFromClasspath)
-                .orElseGet(() -> fallbackClient.get(url));
+        Optional<String> maybeString = handleProtocol(url);
+        if(maybeString.isPresent()) {
+            InputStream stream = this.loadFromClasspath(maybeString.get());
+            if(stream != null) {
+                return stream;
+            } else {
+                throw new UncheckedIOException(new IOException(String.format("Could not find %s", url)));
+            }
+        } else {
+            return fallbackClient.get(url);
+        }
     }
 
     private InputStream loadFromClasspath(String str) {