Clarify some items thanks to users feedback

docs/features/directory-users.md

@@ -3,12 +3,12 @@
   - For SQL: Use `synapseSql` module with `type: {sqlite|postgresql}` and `database` as JDBC url after `jdbc:driver:`
     - `/path/to/db` for `sqlite`
     - `//host/db?username...` for `postgresql`)
-- Configure DNS overwrite for domain name (and mention ${matrix.domain} can be used)
+- Configure DNS overwrite for the Homeserver hostname used when connecting as a client (and mention ${matrix.domain} can be used)
 ```
 dns.overwrite.homeserver.client:
   - name: 'example.org'
     value: 'http://localhost:8008'
 ```
 - Configure reverse proxy
-  - for `/_matrix/client/r0/user_directory/search` to `http://internalIp:8008/_matrix/client/r0/user_directory/search`
+  - for `/_matrix/client/r0/user_directory/search` to `http://internalIpOfMxisd:8090/_matrix/client/r0/user_directory/search`
   - With `ProxyPreserveHost on` on apache

src/main/java/io/kamax/mxisd/directory/DirectoryManager.java

@@ -21,6 +21,7 @@
 package io.kamax.mxisd.directory;
 
 import com.google.gson.Gson;
+import com.google.gson.JsonSyntaxException;
 import io.kamax.matrix.MatrixErrorInfo;
 import io.kamax.mxisd.controller.directory.v1.io.UserDirectorySearchRequest;
 import io.kamax.mxisd.controller.directory.v1.io.UserDirectorySearchResult;
@@ -96,8 +97,10 @@ public class DirectoryManager {
             if (resultHs.isLimited()) {
                 result.setLimited(true);
             }
+        } catch (JsonSyntaxException e) {
+            throw new InternalServerError("Invalid JSON reply from the HS: " + e.getMessage());
         } catch (IOException e) {
-            throw new InternalServerError(e);
+            throw new InternalServerError("Unable to query the HS: I/O error: " + e.getMessage());
         }
 
         for (IDirectoryProvider provider : providers) {