cmServerProtocol: allow 'cache' request before 'configure'

Fixes: #16989

Help/manual/cmake-server.7.rst

@@ -666,8 +666,7 @@ and will not survive the build directory getting cleaned out.
 Type "cache"
 ^^^^^^^^^^^^
 
-The "cache" request can be used once a project is configured and will
-list the cached configuration values.
+The "cache" request will list the cached configuration values.
 
 Example::
 

Source/cmServerProtocol.cxx

@@ -490,10 +490,6 @@ bool cmServerProtocol1::IsExperimental() const
 cmServerResponse cmServerProtocol1::ProcessCache(
   const cmServerRequest& request)
 {
-  if (this->m_State < STATE_CONFIGURED) {
-    return request.ReportError("This project was not configured yet.");
-  }
-
   cmState* state = this->CMakeInstance()->GetState();
 
   Json::Value result = Json::objectValue;