If property fetch fails, use dummy values

src/lib.rs

@@ -174,7 +174,7 @@ impl<T: Runtime> ClientBuilder<T> {
             rpc,
             genesis_hash: genesis_hash?,
             metadata: metadata?,
-            properties: properties?,
+            properties: properties.unwrap_or_else(|_| Default::default()),
             runtime_version: runtime_version?,
             _marker: PhantomData,
             page_size: self.page_size.unwrap_or(10),

src/rpc.rs

@@ -96,7 +96,7 @@ impl From<u32> for BlockNumber {
     }
 }
 
-#[derive(serde::Serialize, serde::Deserialize, Debug, Clone, PartialEq, Eq)]
+#[derive(serde::Serialize, serde::Deserialize, Debug, Clone, PartialEq, Eq, Default)]
 #[serde(rename_all = "camelCase")]
 /// System properties for a Substrate-based runtime
 pub struct Properties {