I realized that the refactor to use ReactDebugCurrentFrame as a decoupled stack frame for error messages is not reentrant: https://github.com/facebook/react/pull/10105/files#r127573520

Fiber is not reentrant but other renderers might be. The synchronous server renderer is atm.

We should add tests for warnings between renderers, such as calling a server-render from within a client render, and update the set/reset callsites to use push/pop instead to account for that.

dontMutate = false;
                nextState = Object.assign({}, nextState, partialState);
              } else {
                Object.assign(nextState, partialState);
              }
            }
          }
          inst.state = nextState;
        }
      } else {
        queue = null;
      }
    }
    child = inst.render();
    if (__DEV__) {
      if (child === undefined && inst.render._isMockFunction) {